Thanks to amp for this info, I thought I would pop it up here for all to see and use:

http://www.audi.com/com/en/contact/contact.jsp
AUDI AG
Customer Support Germany
P.O. Box 10 04 57
85004 Ingolstadt

http://www.audi.com/de/de/kontakt/kontakt.jsp

AUDI AG
Kundenbetreuung Deutschland
Postfach 10 04 57
85004 Ingolstadt

Telefon:
0800 - AUDI SERVICE
(0800-28 347 378 423)

Telefax:
0800 - FAX AN AUDI
(0800-329 262 834)

http://www.audi.com/com/en/terms_of_use/imprint.jsp says :-

Mailing Address: AUDI AG, D-85045 Ingolstadt
Phone: (+49)-841-89-0
Fax: (+49)-841-89-32524
E-Mail: zentrale@audi.de

This one might be more appropriate, I'm not sure. I left the links so people could double check.

Steve - 2002 1.4SE petrol, Silver, black/black interior, Then an identical replacement 2003 A2. Now a Toyota Corolla 1.6 T-Spirit