Frustrated A3 Driver

I have brought my car in to the Audi Centre Johannesburg several times for the same issue, starting in July to .I have had to bring my car in every two weeks since The 1st repair was done. The 1st time my car was there for three weeks before my car was given back to me, I was not even offered a loan car. The second time it came back in it was there for a few days and still no loan car. I was then instructed to keep my car, which was barely in working condition for 2 weeks until another loan car was available. I had that loan car for three weeks and then was told my car was fixed. Two weeks later and my car was giving me the same issue. My car went in again for a few days and we are now in October and my car once again has to go in for the same problem. I have been told that the mechatronics of the gearbox, the clutches and the flywheel of my A3 1.6TDI have all been changed and that all the settings have been redone on my car, repairs totalling approximately R68 000.00, of which I had to pay approximately R10 000.00, but I am still having the same problem. The are only two logical conclusions that I can come to, either the parts that were replaced were not the issue, or the parts were not changed at all. The first would then mean that 1. Your service agents and mechanics don't know how to diagnose and fix the problem, or 2. Are trying to get as much money as possible by changing pretty much every part in my car. The latter would then mean your company or employees have ****** the parts and invoiced them to me. Neither of which is appealing to me because I purchased my Audi from an Audi dealership and brought my Audi to and Audi Service centre, as I presumed it was a Luxury brand and I would get that type of service. Apparently that is not how Audi South Africa works.