Here's a good English-speaking general mechanic just off Langstrasse. He does all makes and is handy with VAG cars:

BERMUDA GARAGE GmbH
Gasometerstrasse 7 (next door to Blunt's Tea Room, by Josefstr.)
8005 Zürich/ZH
044 273 48 00

I've no connection to the business.

Here are a couple of threads which may be of interest 1) 2)