1MIOflight-km - Ever since the restrictions imposed by VISA/Plus-Banelco in February 2007, no US or European VISA debit card holders have been able to receive any kind of explanation from their home banks as to why the situation evolved. The expat bulletin boards have hundreds of threads describing the frustration of expats with their home banks seeking an explanation. So I wouldn't expect your bank in Germany to be any more forthcoming.
John