I've just tested the USSD-menu (*104#) with my Tchibo SIM and I could access it flawlessly. Anyway suppose your problems are either caused by some component on the O2 network, as the error message comes from Tchibo or the USSD-menu is inaccessible from roaming networks.
According to
this German wiki Tchibo SIMs used to remain active for 365 days after the last recharge, but since May 2010 they are active infinitely.