Arrears on device returned and collected by couriers

Gud day to u..in my last review I mentioned that I was being told by cellc that I'm in arrears for a device that I returned in January 2021..I also mentioned that I received a call frthem saying they received the device but I returned the wrong one..he also told me that the reason I never received notification about this is because it was a cash contract..which I never heard of..since I wrote my review I was contacted by someone from cellc and she did her own investigating..she has since told me that there is no record at RAM COURIERS of this device..how can this be if I received a call about a cash contract and confirmation that they did receive it..cellc makes me sick..truly..I don't have any documentation of when they collected the device..I just wanted to return it asap