Patientline, which provides bedside communications systems for hospital patients, yesterday removed its chief executive of less than a year as a group of rebel shareholders announced their plans to oust chairman, Derek Lewis.

The dissident shareholders, led by stockbroker Shore Capital, will today call for an extraordinary general meeting at which they plan to oust Mr Lewis, former director general of the prison service, and replace him with their own candidate.

A source close to the rebels said the departure of the chief executive, Per Jonsson, a former General Electric executive appointed last March, made no difference to their plans.

"As major institutional shareholders our patience has been stretched to the limit by Lewis' inability to confront the problems facing Patientline. It is time for him to go and we will be issuing a statement," the source said.

The shareholders blame Mr Lewis, the former director general of the prison service, for Patientline's poor performance. Mr Lewis was chairman when the firm listed in 2001. Its shares have fallen nearly 80% in the past year, hit by poor demand for its services and an investigation into bedside call charges by Ofcom, the communications regulator.

The company had hoped its sophisticated systems, which have been installed in 120 hospitals, would be used to display patient records and low resolution scans as well as to provide interactive services such as food orders. But so far there has been little demand for these extra services and one of the few ways the company has been able to recoup some of the £130m it has spent is through incoming call charges costing a minimum of 39p a minute.

Mair Barnes, Patientline's senior non-executive director, said that Mr Lewis had the unanimous support of the board.

"Patientline faces a number of challenges over the coming months. Derek's specific experience and expertise is considered vital in securing the best outcome for all Patientline shareholders, particularly given the departure of Per Jonsson and the appointment of Colin Babb as Group Managing director" she said.

At the behest of Ofcom, Patientline is in talks with the Department of Health to see if the cost of incoming calls can be reduced and terms of its licence changed.

Ross Graham, another non-executive director, said that Mr Lewis would play a crucial part in those discussions. He also expressed surprise that shareholders wanted to remove Mr Lewis given that he reaches retirement age in the summer.

Mr Lewis said he was disappointed by Patientline's share price but it was not surprising given ward closures, NHS changes and the Ofcom investigation, which was finally brought to a close last month.

He denied claims that the removal of Mr Jonsson, who bought £11,000 of shares on January 19, was an attempt to placate the rebel shareholders. "We needed a level of operational leadership that he was not able to offer. Per had not worked in the UK or with the NHS before."