air-con stuck on and wont stay on degrees C

[pidsy]

so, just had the front end of the car resprayed, battery had been disconnected for obvious reasons. the aircon unit is now stuck on "Auto" and i cant get it to stay on degrees C.

i know to change between F and C is to hold the auto button and press the front screen de-mist button.

this works fine until i stop the car. the next time i start it, its back to degrees F.

i cant turn the Auto button light off either.

am i doing something stupid?