The First Division Association has raised concerns about the treatment of managers involved in trust mergers after taking legal action on behalf of a former Welsh ambulance trust officer.
Jon Restell, the FDA's NHS officer, said the case of John Beecher, former chief ambulance officer of Mid-Glamorgan Ambulance trust, raised 'wider issues'.
'The creation of a single ambulance trust being seen as a model for the bigger trust reconfiguration programme in Wales,' he said.
The FDA claims that Mr Beecher applied for the post of regional ambulance officer in the Welsh Ambulance Services trust, which took over five ambulance services earlier this year. It says that in September he was offered project work on a six-month contract.
In an affidavit for a court hearing last week, Mr Beecher claimed the new job would involve a drop in status and increase his trip to and from work from six to 94 miles.
On 1 October, Mr Beecher claims he received an ultimatum to accept the offer or be made redundant. He rejected it and was sent a letter saying he was entitled to a redundancy payment.
The FDA and Mr Beecher claim the trust then served an injunction seeking recovery of the£46,828.13 redundancy payment, saying it had been paid in error. Mr Beecher then received letters saying his bank account had been frozen.
The FDA is planning to fight the trust's recovery attempt and claim damages for breach of contract.
Welsh Ambulance Service trust chief executive Don Page said the case was in the hands of solicitors, who declined to comment.