if theres no makers name on it its probaby an unbranded one from one of the diy sheds and as such not worth messing around with
good news is they are cheap as chips probably from £50 upwards and they are easy to change
The thermostat is faulty, just keeps going hot/cold by itself. I think it would be better to just renew as to track the parts, most new ones are cheaper than parts nowdays.