The FBH stopped working awhile ago and the gap showed the following fault :
B12A6-15 (2F) Auxiliary heater water pump - General electrical failure - circuit short to battery or open.

Was planning on getting it sorted but never got around to it, anyway needed a new battery a week ago and low and behold the FBH worked the next day. Then on the second day using the remote (outside temp 5 degrees ) only cold air coming out of the vents. Not only that the blower was still blowing when I got in the car, usually the system turns off when I press to unlock the doors. Checked the timed climate screen and both sections were greyed out. The next day it worked and the car heated up but for the last 3 days only cold air being pumped out. I usually check it’s working by touching the bottom of the windscreen and if warm know it’s working.

Anyone had anything similar or any ideas ?

Check the wiring I'd say.