Here's an update - Many thanks to VW.Man for information I have managed to fix it for now without any invasive action.
My first issue was finding the motor and it is just visible on the passenger side in the footwell. In order to see it comfortably I rigged up a platform outside the car at sill height then put cushions in the footwell to support my head and in this way I could lay quite comforatbly and look directly up. Once I identified the motor (Green/Yellow, Purple, Yellow, Black and Green wires on connector) I unplugged the connector and made a connector out of an old PC power supply floppy drive plug cut down to 2 terminals. I connected this to a battery and by placing it on the Yellow/Green and Purple connectors (the two in socket that are grouped on there own, if you look at the plug it is grouped as 2 and 3, the 2 are the motor and teh 3 are the feed back potentioneter) I was able to drive the motor forwards, then reverse the plug and it drives the other way.
I was really only trying to set it to a cool position, but I thought I would plug it back in and see what happened, as luck would have it it has now started working normally, you can watch it respond to changes of the temperature setpoint.
So I guess for me the issue was the feedback potentiometer and driving the motor has fixed it for now
Time will tell for how long.
If there's any interest i will put up a photo of my made up connector
Best regards everyone