I would try to call German Rail (49) 1805 99 66 33 immediately. I don't know if they have anyone (particularly English speaking) on staff on the weekend, but you really need to tell them. I don't know if they can change it now, or not, but try.
When I registered with the Bahn almost 10 years ago, just for access to information, not expecting to buy tickets with that registration, I used my nick name, not my legal name. In 2008 I purchased Dauer-Spezial (now Sparpreis Tickets) from the Bahn. Not realizing that the names were different, I used the registration. When I printed the tickets, I noticed they used my nickname, not my legal name on my credit card, and, since my legal name and nickname are not used in Germany, I called and asked them if the conductor would understand that it was a nickname. They said the full name and the last four digits of the card number are all important, but he couldn't change it. I hung up, expecting to have to change the name on my card (you can do that). Fifteen minutes later I received email from the Bahn with new pdf files with the name changed.
Good luck.