Someone should bring a lawsuit charging fraud and see how they like it.
Lawsuits aren’t magic. They’re lengthy, difficult and expensive, and in this case would almost certainly be unsuccessful : when the customer opened the account they consented to Terms &Conditions which undoubtedly include a clause that the CU can change them. As others have suggested, the thing to do is to change to another bank
Could be a case of them practicing “an illegal restraint of trade”.
Any lawyers here want to comment?