Canceled and still getting charged!

In April I received a pocket router and a Home wifi router. I sent the pocket router back as I didn't want it anymore. I signed for receiving the Home wifi router and sent the pocket router back with the courier without signing for it as I didn't take it.

During April and May I have contacted Telkom numerous times to cancel the Pocket router, but I still got debited on the 25th of May.

This meens I am now paying for a product that I don't have and no one seems to be willing to assist.

Cancel and reimburse, that's all I want.

A very simple request that they can't seem to be following.