Return of ADSL Router

Dear O2 Experts,

Yesterday I went to the O2 store and asked for advice on :

      1. Assure that my Handy contract is not renewed.

      2. Cancelling my ADSL contract. It is a monthly contract.

      3. Sending back the router. I brought in the router with the paid stamp and address.

In relation to 3, he said that the paid stamp and address in the box is designed to be used for the  return of the router if it is faulty. He then attempted to print out a new paid stamp and address, but couldn’t because the O2 website was having technical issues. What is the address for sending back the router ? What is the process ? I have read a few posts where it seems that routers were sent back and logistics department did not record the return of the device. It is disconcerting.

Kind regards,

Spottie