AUDI A5

My vehicle is with the brance since 17/06/2015, the car keep cutting out while driving, I have received it back on 24/06/2015 with a oil leak which was repaired with silicone. The car went back, I received it on 03/07/2015 with a huge engine noise. After it went back I receive the car on 30/07/2015 just for the car to breakdown the following day with excatly the same problem it went in on 17/06/2015, I really now need assistance with this matter because I have reported it to HEad Office on the 15/07/2015 with no phone call from them. I have a copy of the e-mail which I send to Head Office for your review, because I battle with this car with the same problem since I bought it in February 2013