Hi, Try reading a thread on the A6 C7 forum by Big Townz that will give you a good insight into whats happening if indeed your cars timing has slipped, do you know the cam belt change history and the other thing I would be asking is what the codes are that led them to deduce timing belt failure, read the thread intensively and see if any of your data matches, £1200 seems pretty steep for a cam belt change I recently had mine done at a good independent garage for half that and they used an O.E. kit from TPS with a two year guarantee [unlimited milage] which is manna from heaven if like my car its being used as a cab.
Steve.