Poor service

VW S.A. and Barons PMB treated me in a way that I didn't think they will, they took my car on the 18th of August for oil service only to find there are many problems in my cars engine, so still today I don't have a car to use but I'm still under warrant as my car still has only 21 000 km ,they don't even want to give me a courtesy car ,I really need your help.