We are not permitted to do entry only under our contract with Berlin as a Travel Partner. If someone has an individual entry it may prove difficult to swap it as you have to show photo ID along with your registration letter to collect the race pack.
I take all your points and accept that the t-shirt offered in 2011 was not to the standard we had expected and supplied to us in previous years. This was a sponsored item and was not in your entry fee.
Clearly there are other events and you are perfectly entiled to be annoyed and avoid our event in future - it is something we will have to contend with and correct in future but not something we can do anything about retrospectively.