Intermittent flap failure

FFS ....... I'm slowly rebuilding my car LOL

Noticed that the flaps didn't open in sport mode the other day.
Car is booked in for a week on Saturday.

Today it worked fine - then just on the last dual carriageway the bloody thing failed again.....

So it seems to be an intermittent fault.
I can just see it now - they wont diagnose the sodding thing !

Anyone else had an intermittent flap issue - I hope it gets worse