Is there such thing as a 'Military clause' in TMobile Germany for US military customers?

We have been battling with TMobile online customer support and they keep on insisting that we pay the whole contract amount. Which is ridiculous because their Marketing agent assured us that we can terminate our contract anytime as long as we have official orders. This has been going on for more than 4 months now and we are going nowhere. What is the best thing for us to do?