Door module/latch is a common
problem with VAG cars. You can replace the part yourself, it's not that difficult and cost is around £130 for a new latch/module. Fitting the card back is "fun" if it's electric windows, the door card design/window mechanism was designed by someone mentally ill and high on meth.
Rear demister could be a fuse, bad wire etc.. when you press the demister button, do you hear a soft click (relay)?