Parts missing in the CAR

My story is one that I would like to report because this problem/issue that could be happening to thousands of other VW customers out there. I bought my car Polo Vivo at VW Hatfield I have been doing my services with them until the day I decided to sell my car . When inspection was done on the car I found that the VW cover that covers the engine was removed and some bolts that hold the engine were missing. This is very interesting because the last and only technician that worked for the company has left so there is no one I can point to. The only person who worked on the car was Joshua. When I tried to contact him, he avoids me on his cell phone which raised a lot of concern. I have gone to different garages and they tell me that certain parts are missing. This is a huge concern to me because now I am asking myself if services were really rendered or was I just getting **********. I stopped doing my services at VW due to the above matter because I just felt like my car was never really serviced. I love VW Hatfield I have recommended it to many of my family and friends, but this issue is bothering me, and I can’t keep quiet about. I am not sure what is supposed to happen in this matter because client relationship and trust is broken and this matter I plan to take the matter further.