I got a voicemail menu where the best option seemed to be "3" ("other information" or something like that). That prompted me to enter my contract number or access code, or to press zero to be connected to a person. I pressed zero and got told that my call would be connected to an English-speaking person (why that, if I called a German TAC? No matter, my English is fine).
But then another voice said "You have reached a number that is not in service" and shortly afterwards, another saying "Disconnecting call".
How useful -- transferring callers to a nonexistent number. Lack of coordination in the company hierarchy? Or what?
Edit 17:28: To their credit, they did respond pretty quickly to an email where I told them of my problem. The response (addressed to "Dear $Customer$"...) gave an email address as well as a phone number in the Netherlands(? - I'm assuming the leading 31 is a country code not a national prefix).
Update 17:48: They don't do technical stuff, though -- only sales and "customer service". Bummer. The email did say "You can reach technical assistance in Germany by using one of the following meathod[sic]." (emphasis mine)... but at least the friendly chap on the other end of the line offered to send me a list of retailers in my area who would be able to answer such technical questions. Better than nothing.