Returning the router at end of contract

Hello,

I have already requested last month to cancel my DSL Internet contract end of March'16. I have received the confirmation that its done, but have not received any return slips for DHL from O2 to send the Router back to O2. I found in the help that I can use this link : RETOURE Online - Telefonica Germany GmbH & Co.OHG to send the router back to O2. Can you please confirm that my account is really marked for cancellation end of Month and this is the correct process to send back to Router to O2. Please confirm on the same ASAP as I have to send it back sharp as leaving Germany end of this week.

My Customer # is DE14045633

Regards,

Suman Chakrabarti.