I have found BA IST being extremely efficient to work with in the past. I do not know the current situation for the last couple of weeks, however, but it would be very weird if the German desk in Bremen is less competent in dealing with these issues than the BA people at IST office were, even their airport counter people are very friendly and responsive. Valid ITN and the locator obtained for their RTW desk UK (they will hold it for 30d no questions asked, as do the US BA RTW staff, btw)...

I do not know you way of communication with BA, but I have personally found out that nothing beats good old phone conversation, then you (usually, atleast) have the agents 100% attention to your case. Emails and faxes are easilly forgotten etc.

Sorry to hear you had promlems with them...