Couple' warm days recently so finally swapped in a new ac compressor. Booked into Halfords Autocentre for full ac service (£49) which includes the regass. Went through the vac & leak test. Charged. Leak tested again. I'm sat in reception and hear a car cranking, trying to start. Thought it may have been my 1.8T BEX though couldn't be sure. This went on for about 20 minutes on and off. Guy finally comes through and says: "Have you had any problems starting your car? Any trick to it"? In 11 years of ownership my A4 has always started first time, every time. I couldn't understand at all what they might have done during the air con procedure to compromise ignition?! Comes back after another 20 minutes and says: "If you zap the car open with the fob it doesn't start in the ignition. Immobiliser is kicking in. If you unlock the door with the key (manually) then boom it starts straight up". So off I drove (with icey ac). I got home. Scanned it. No codes. Key was working fine for me (remote unlocking). I've tried to replicate and no luck. The exact same key on remote, ignition, all working great. The only thing I can think of is that the car was locked but they were leaning in through the open window (car came out with drivers window fully down) trying to start it when it was actually locked (and armed) maybe? But then the interior alarm should have triggered?! Surely if you remote unlock the car the immobiliser registers that as 'authorisation' and should start in ignition? Anyway, I'm all good now(!) but just wondering if anyone has any experience of such a (key fob?) issue. Maybe intermittent if the key fob battery is dieing. For me it meant sitting in Halfords for an hour longer than I might have liked!