A friend is having much the same problem. Thermostat is stuffed and I am having trouble getting a new one for them. There are two thermo stats, one mechanical that looks after the food compartment. Sounds like your problem is in that area. If I find any fixes I'll let you know.
repairs can be dangerous.
In many instances work should only be undertaken by a qualified
professional. Ensure you have read our Small
Print page before using information supplied via this website.