I booked a ticket with them,too. This guarantee is bull....!
I´m now in talks with the German director of that airline to verify their argument which was that the ticket booked on tq3direct.de is a corporate fare and tq3 is not allowed to sell this to the public...if the director confirms this I will let them go if not I will go to court.
Already in talks with a very famous German lawyer who is specialized in travel law...