Dhl packet station

As we were not at home for about 2 weeks to collect the parcel, our packets are going back to the sender. Unfortunately the sender has vacated the room now. So what can be done to retain the parcel to the destination packet station? Dhl customer service is not reacting properly for English speakers!

As far as I know, a parcel that cannot be delivered is stored in the nearest post office for 10 days (or so). If it is not collected during that period, it is returned to sender. If (as in this case) it cannot be delivered there either, I assume the same applies (storage at post office for 10 days), after which it is destroyed.
Thus please check whether the sender can collect it from the post office in a timely manner. If not, the DHL customer service is your only chance. (If there is a language problem, maybe you can ask a German friend to help?)