Problem with order delivery

Hi

Problem: I speak only English and I ordered a Smart Watch from O2 in contract. Product wasn't delivered to me and delivered back to O2 for some reason. But O2 sent me email that ordered has been delivered successfully. I filed return which says return your product through DHL. I can't contact anyone on Kundenservice. I am not sure what's the status of my product now. Does O2 know its already returned? Can you please tell someone from O2 who speaks english to call me and resolve my issue?

Regards 

Syed Muhammad Ammar Sohail