Car repair

Hi, you know I am really frustrated now. The panel beater Autohaus, I feel they don't want to release my car. I have a live tracker in my car and I observed its was driven from VW at speeds of 140km ph. However I am told the car is not ready for collection due to wrong parts again and again. Excess was paid a week ago in anticipation that would get it back on the 28 Feb. How do I get my car back coz at this point I feel they pushing work time. Very bad service wouldn't recommend.