If IKEA refuse to budge then you could try the link below for a local engineer...most if not all will have a smaller call out charge than £70!!!
Besides...it will likely be something minor...the inlet regulator's prone to problems and the fact that it has been unused may mean it needs a techincal adjustment (judicious thump with a flat hand!) to revive it
This part is located inside a water chamber inside the cabinet so not a diy job unless you are confident.
If you have a go yourself then you must unplug before doing anything