Returned iPhone to Telkom

Hello, I ordered an iPhone 13 from telkom last year November and it was taking time to be delivered and I was going home for 3 weeks I decided to cancel the order only to find out that the devic will be delivered on the 5th of February and I returned it back with the courier lady I have all proof from courier campany to show that they returned the phone but I'm being told that the device is active and it is still under my name and yesterday I got statement from telkom showing that they will be debiting my account R498 on the 15th for a phone that I returned please help me because I tried calling them but they are asking me where is the device now and how would I know when I returned it. I'm suspecting that the device was ****** and sold hence the return was not captured in their system please help with this