Paid R10k for nothing!

Bosch car service centurion continues to disappoint me after promosing to come back to me. We send our Polo tsi for repairs and paid R10k but the car was not fully repaired. I took the car back to explain that the car is not properly repaired, they took the car in for the day and they insisted that the car is fine. Lodged a complaint at head office in November but nothing came out of it.