*ignition coils keeps failing*

I have an Audi B7 2.0t S-line, very low km. +-8 months ago I replaced the ignition coils in Paarl through a mechanic.<br> <br> 2 months ago I noticed a problem with the vehicle and took it to Audi whom informed me that two of the ignition coils needed to be replaced. They also recommended that if one is faulty it is best to replace all four. I remembered they were still under guarantee by Bosch so I decided to go back to my mechanic in Paarl.<br> <br> 1) Mechanic informed me that Bosch only replaced 1 coil even after Audi said 2 coils, because BOSCH only found one faulty! R150 petrol from Somerset West to Paarl, R250 transport costs home again. And again another R150 to fetch my car. Total R550<br> <br> After few days same occurrence. <br> <br> 2) Mechanic informed Bosch about the time, labour, money wasted. BOSCH now replaced the faulty ignition coil that Audi mentioned on day one. R550 transport costs again<br> <br> 3) Today after fetching my Audi the same occurrence. AGAIN IGNITION COILS! <br> <br> I HAD IT BOSCH! It will be R1650! I don't think this is good for my car neither? Why not replace all 4? I am extremely disappointed with the service from BOSCH. If I knew this! I would have not purchased them!