With me, I lost movement in both planes at the same time. Dealer diagnosed it as a connector that came away from the switch. I was still under warranty at the time, so it was n/c. I suppose it's possible to lose control in one plane and not the other with a loose connection, so popping the oval shaped panel off to check is probably worth a try.
The seat heater control buttons and the mirror control knob just pull straight up. The oval cover then needs to be gently pried up with a very thin lever. Once off, you have access to the switch assembly, which is held in place with about 4 or six clips that are positioned vertically around the assembly. Keep a pencil type magnet handy in case one drops into the space below the assembly.
Good Luck
