High Court action is being taken against a Birmingham telecoms company less than a year after it was fined almost £184,000 for stopping customers from switching to rivals.

Regulator Ofcom launched the action after dozens of Telephonics Integrated Telephony customers said they were still being stopped from ceasing ties with the firm despite a record fine of £183,898 in August 2009 for similar offences.

It found that in some cases they had been threatened with solicitors’ letters demanding thousands of pounds in early termination fees even though they had given the required notice.

Other customers of the Erdington-based company complained that Telephonics changed the terms and conditions of their contract after they said they wanted to switch away.

Last August’s fine was the maximum amount that Ofcom was permitted to punish firms – 10 per cent of turnover.

At the time Telephonics was told to comply with the rules in future, but Ofcom said since then it has failed to either pay the fine or operate within the rules.

One Telephonics customer who decided to switch to another company complained after he received a copy of his contract from the company which appeared different to the one he had originally signed.

He said: “It was then that I found that the terms and conditions on my contract were different to the contract I had just received from Telephonics.

“In the Telephonics contract there was an additional clause that stated that £3,000 was payable for early termination of the contract. I had received no notice of this change to the contract.”

Another customer was told by a Telephonics employee that he would cut her off if she did not withdraw her termination request.

She added: “I said, ‘Are you threatening me?’ to which he responded, ‘No, that’s not a threat, I will turn your phone lines off’.”

A third customer decided to leave Telephonics in December 2007 but his attempts to transfer his services “were blocked on at least six or seven occasions between December 2007 and October 2008”. “It was not until 23 October that all of our telephone lines were successfully transferred away from Telephonics,” he said.

Proceedings for Ofcom’s case against Telephonics, which is registered to an address in Kingsbury Road, Erdington, have already begun before the High Court of Justice (Chancery Division).

When the company was fined in August, Ofcom also revealed it was investigating the company over separate complaints about slamming – where a phone contract is switched from one operator to another without the customer’s knowledge.

The regulator said, in a statement: “Ofcom’s investigation found that when Telephonics was contacted by rival telecoms firms, they did not use this information to begin the transfer process.

“Instead they used it to cancel customers’ requests to transfer away.

“They also rang their customers to try to persuade them not to transfer away, which is also against the rules.”