Birmingham Audi

I've owned my Audi A4 for 2 years and have used Birmingham Audi for regular servicing and warranty work. While they appear to carry out standard services satisfactorily (apart from an oil/filter change, there's actually little to do), they seem incapable of dealing with any warranty issue which "doesn't give a fault code" which makes dealing with them a most frustrating experience. I'd rather not have the free coffee & biscuits and be able to talk direct to someone who actually has some level of technical competence. My impression is that they're not really interested in private customers but are geared towards business users and are essentially a sales operation which does the minimum necessary in terms of providing servicing. Unfortunately, Listers have a monopoly on Audi dealerships within the general area and the others I've visited seem to be run on exactly the same lines.