bought this car 6 days ago(sold as seen. no comeback for them!)on the way home i stopped for petrol(gas). tried to put the thing into drive and it wouldn't let me! husband fiddled and we managed to get home. although the gear changing is slightly jolty. read in the manual that it is the car protecting itself. gone into "Back up programmed mode" because it has detected a fault in the control system. can't find any info anywhere to tell me if the problem is electrical or the the gear box is shot(to put it politely) have been told by Audi to take it in for diagnostics."if it's what i think it might be missus(scratch nuts and smile) it will cost between 2 and three thousand pounds. anyone know what it could be?