File this in the no good deed goes unpunished box.

OP chose to buy in advance, the terms are clear and he chose to leave the thing back in the UK.

Not one whit of an obligation to replace the ticket, but they will if he brings it to the office when he is next in Berlin. His sole penalty will be having to eat the cost of the airport-downtown.

Can assure you that this wouldn't be handled quite so nicely for a visitor to NYC, LON or TKY.

Perhaps a change to the thread title, "I made an error an am getting what I'm not due to make me feel welcome."