Fridge Selector Switch

We have a Rienza 2006 and the Dometic fridge Model No RM7271 and the energy selection switch is stuck on battery operation.
The knob  turns but when it is on 'OFF'   'GAS'  or  '230v'  it is still stuck on Battery operation?
Help please.

I guess you mean that the 12V lamp stays lit, no matter which position the switch is in, even with the engine switched off? One possibility could be a fault in the fridge 12V relay (which should normally only engage when the alternator is producing power). But if this were the problem I would expect your vehicle battery to go flat pretty quickly if the switch is left in the 12V position...

  We had problems with the fridge in our Rienza, unfortunately not the same as yours. If it is any help Greentrees at Derham sorted mine after a bit of messing. I noticed when the vents were off to repair ours there was a relay behind the bottom vent. Maybe try unplugging this and see what happens. As said if the relay was stuck the battery would be flattened fairly soon. The guy that sorted ours was Jorge, that is the correct spelling.
Good luck.