Singer Gareth Gates was so delighted with his hair transplant he tweeted that anyone thinking about having the procedure should “go to KSL!”. The brand claims to be “the leading hair loss clinic in the UK” and boasts that its happy clients include stars of TV show The Only Way is Essex, and former X Factor contestant Jake Quickenden.

But dig around on the internet and a different story seems to emerge: one involving what appears to be a lot of unhappy customers, some of whom claim they handed over as much as £9,000 to a KSL company for treatment, but ended up enduring a nightmare experience.

A Facebook group called “KSL Hair The Truth” has been set up and features posts from people such as Jerry Smith, who claims the two procedures he underwent were “traumatic and horrible” and that he had been left “financially broken and emotionally broken”.

The forums of the website Bald Truth Talk also feature a number of complaints and there is a Twitter page that has published what appears to be a number of unfavourable reviews and photos.

But when Guardian Money spoke to the KSL Clinic, it told us that all the problems and issues relate to two other companies, KSL Hair and KSL Medical, and that the KSL Clinic was a “completely separate” business that has “absolutely no current complaints against it and never has had”.

The KSL Clinic may be a separate business now, but its history is intertwined with the other companies. All three either are, or were, based at the same Glasgow address.

Meanwhile, a man called Simon Lindsay is a director of both KSL Hair and KSL Medical, and was, until last September, a director of the KSL Clinic, which he co-founded in 2016. And when Money checked the KSL Clinic website earlier this week, the company number and registered address given was that of KSL Medical.

On top of that, the KSL Clinic website describes it as “UK hair loss specialists since 2013” – even though the company did not exist then. That was the year KSL Hair came into being.

Jerry Smith said he had a consultation with KSL Hair at its Glasgow clinic in January 2015, conducted by Lindsay, and agreed to have a transplant procedure at a cost of £9,000 (later reduced to £8,000). But he claimed: “The two procedures from KSL were a traumatic and horrible experience. They have damaged my body beyond repair and decimated my donor area ... I can honestly say KSL was the worst mistake I have ever made and I hope all of us affected finally get our justice.”

Another apparently unhappy client who has posted on the Facebook page is Chris, who said his first procedure was carried out at the Glasgow clinic in April 2016 and claimed that “the only thing that seems to be growing is Simon Lindsay’s bank balance”.

Many of the complaints on the Facebook page and elsewhere appear to relate to KSL Hair. Another unhappy punter is Michael Gemmell, who wrote on a reviews website last month that he had had two transplants at KSL Hair’s Glasgow clinic.

“My results are embarrassing and I’ve been left with horrendous scarring as a result of malpractice and very poor standard of work ... please do not be fooled into handing over any money,” he says.

This is, presumably, the same Michael Gemmell who, according to an official insolvency notice, is being represented by law firm Jones Whyte and went to Glasgow sheriff court earlier this month to seek permission to bring proceedings against KSL Hair.

The number of KSL companies (there are at least six) complicates things somewhat. What’s undeniable is that the KSL “brand” has had a bumpy time of it recently. A spokesman for the Scottish healthcare regulator that registers clinics told Money this week that it had received “a number of complaints” about KSL Hair.

The regulator, Healthcare Improvement Scotland (HIS), adds: “We take complaints from members of the public very seriously. As a matter of policy, we do not comment on ongoing investigations.”

KSL Hair was voluntarily wound up last October and is currently in liquidation.

Meanwhile, KSL Medical – which is based in Glasgow and was set up in January 2017 – has announced on its website that it has just had its licence to perform hair treatments suspended by HIS.

On the site, Simon Lindsay, who describes himself as company owner/director, states: “I would like to offer my sincere apologies to any customers that we have let down in any way.”

He adds that he has been advised that the firm is not legally permitted to carry out any of its services.

Back at KSL Clinic, the company says on its website that it “is set to continue providing its award-winning hair restoration services,” and will now be operating primarily from Maidstone in Kent, with support from its newly opened Manchester clinic.

“We’re the busiest clinic in the UK, and we’re proud to have treated so many high-profile celebrities,” it says, adding that these include James Lock and Mike Hassini from ITVBe show The Only Way is Essex, and ex-All Blacks rugby player Xavier Rush.

So what does the KSL Clinic say about the issues highlighted here? Lloyd Hume, who set up the KSL Clinic with Lindsay and is still a director, told Money that “by the middle of last year I was a little unhappy about some of the issues arising from KSL Hair and KSL Medical”. As a result, he says, it was agreed Lindsay would resign as a director. Hume says he agreed to buy the KSL web domain rights in February this year.

Asked why his site carried KSL Medical’s company number and address, Hume says: “It’s an oversight by my media company.” Hours after Money pointed it out, this was changed.

Hume claims some of the people posting on Facebook “have got personal vendettas against Simon”. Of Smith’s case, Hume says: “I can’t comment. He had his hair done in Scotland in 2015. My company wasn’t even born then.” Of Gemmell’s case, Hume says Gemmell made contact with him, and “I tried to give him as much help as I can.”

He adds: “These are historic problems.”

Meanwhile, in a statement, KSL Medical told us: “Mr Lindsay cannot make any comment to you regarding any former client of KSL Hair or KSL Medical due to data protection laws and patient confidentiality. What I can say is, every client of KSL Hair and KSL Medical signed a detailed consent form before proceeding with the treatment, making them aware of all risks and expected results.

“We have always done our utmost to resolve any issue with a KSL Hair or KSL Medical client.”