Fastest way is to do it in a sell-point with the purchase card (credit card) and receipt. Do it via post always takes forever. Normally it helps to be rude with them via post.
So, i can write something for you in german if you give me the travel data, etc. (PM) and see if it works out or not. But those tickets normally cost 29 to 49€, which are diminished by the 15€ service fee, so if you want to do it just for the heck of it fine, but its 34€ max... you could just let it be as it is as well...