Sorry for the late reply, been busy. The heater matrix was blocked and had to be replaced, all good now. The dealer I bought the car from repaired it for me, free of charge, which probably cost him a fortune as he had to buy matrix from Audi. He did say its something he's going to check on any audi trade-in from now on. So if anyone is buying private please check this.
Cheers
Gavin.