At the end of 2015 my partner and I joined our local DW Fitness Clubs gym in Manchester, but after six months decided to cancel our membership. We were told this could not be done in person and were given a telephone number to ring. The number – 0344 249 5300 – was never answered, so I called our gym directly and was told that our membership had been cancelled and an email would confirm this within two days. The email never arrived.

We then began to receive emails informing us that our direct debits had not been paid and that our membership was in arrears. So back I went, where the gym manager said that unless I could prove the phone call had been made, I was still a member. I asked if he would cancel for me and was advised that he could not do this. He was rude and unhelpful.

We have now received a letter from ARC Europe debt collectors threatening us with legal action. Can you help? LB, Manchester

• In May I went into my DW Fitness Clubs gym in Southport to cancel my membership of four years. A member of staff logged me onto a computer then left me at the terminal to complete the form. I was informed that I would have to pay for May and June to complete a whole month’s notice.

After June’s payment had been taken from my bank account I cancelled my direct debit. I tried to phone the customer service number several times but could never get through.

The company claims it has no record of me handing in my notice and that there was no computer terminal there at that time. It also says I have to pay for the months since, plus an admin fee, or legal action will be taken. I feel it is harassing me and claims I am not telling the truth. Do you have any advice? HB, Southport

We have had a significant number of complaints about DW Fitness Clubs since we ran a letter about the company in June – and almost every one is from a reader who is trying to cancel their membership, but can’t. DW Fitness Clubs operate 92 gyms around the country, but in our and our readers’ experience no one ever answers its cancellation line.

Others who have been into the gym in person, who thought they had cancelled, have come up against a similar experience. They feel that the company makes it as hard as possible to cancel contracts to maximise revenues.

We emailed these complaints, and several others from readers, to the firm last week, but were baffled by its response. It said we must send all letters by recorded delivery and that it would only deal with them in that form. This is an absurd stance in 2016 and one that makes us feel sympathetic to the obstacles others have experienced in dealing with the company

In 2013, the Office of Fair Trading examined Dave Whelan Sports (the parent firm) as part of an investigation into gym-sector contracts, and said at the time that the firm had “worked constructively with the OFT to make improvements to their terms and conditions, associated documents and sales processes and have signed undertakings to address the OFT’s concerns”.

In our view, perhaps the authorities should take a second look at this firm. We would advise any existing customers to film and record proceedings on their mobile phone when they cancel, so there can be no dispute later.

As regards the above cases, we would advise the readers to stick to their guns and tell ARC that they dispute the debt. Send copies of the correspondence as proof. Or you could pay DW Fitness Clubs and then sue it in the small claims court, depending on how bullish you are feeling. We recommend you also complain to trading standards that this is an unfair contract. Citizens Advice has a page on its website on how to dispute a wrongful debt.

Based on our dealings with this firm, we would not be about to sign a gym contract with it and would urge members to wary in any future dealings. As DW Fitness Clubs declined to respond to the issues raised, we will report back if that situation changes.

We welcome letters but cannot answer individually. Email us at consumer.champions@theguardian.com or write to Consumer Champions, Money, the Guardian, 90 York Way, London N1 9GU. Please include a daytime phone number