TT Mirror not demisting

[Audi Bairn]

Been using the wifes TT to even up the mileage a bit on the two cars.
Noticed the past two mornings that the drivers mirror ain't demisting (the passenger one is).
Any quick fixes I can do myself? Trying to avoid a garage trip if poss.

 

[NHN]

Swap sides to test heated glass, if works on drivers then it's the glass, but feel free to test drivers on passenger side too.

 

[Audi Bairn]

Car went in to dealers on Saturday.
Was the heating element, so glass etc changed under warranty so all good now.