We’d need a model to be sure but it sounds like a classic module failure on a Servis which is a very common problem with them I’m afraid. And Servis are having a laugh with the spares prices, most of the modules are a few pounds shy of £100!
Yes, I know that’s half the cost of of a new one. 🙁
EMW do reworked ones though and a lot of the guys on here use them so you could try the directories or Repairs@ for a local repairer and, if you don’t get any joy there, let us know what postal code area you’re in and we’ll see what we can come up with.
K.