Billling

I took my car (2009 Audi A4 Multitronic Avant) in for repairs at Bosch Giyani Service Centre (28 August 2015) and according to their Diagnosis they found that the transmission was faulty. I was given a quote of R 26651.95 and I had to pay an amount of R23142.00 for them to replace the transmission. This dragged on up until today (27 October 2015), as their unable to fix the transmission. I had to make daily calls to request for an update. I ended up calling Bosch Customer Care to launch a complain and they called the service centre and they now coming up with a new quote to say that I need to replace the torque converter which amounts to an additional R10 000. My car is currently held up and I cannot afford to pay an extra R10 000. What's strange is that this dignosis comes a month after the car was with them. I'm not even sure that they did the right diagnosis on the transmission.All I want is for my car to be fixed or my money back and I'll take my car somewhere else. I've been making numerous calls without any help. This is one of the worst customer service I've received so far.