Return not handled

We bought an action camera from takealot for my son for his birthday. He also got money from the family so he decided to rather return the camera (never used it) and use the money to buy something else. I returned the camera on 15 March 2022, but forgot to put the charging cable in the box. My mistake. I received a mail on 22 March that the cable was missing. I delivered it to the pick-up-point in Old Jhb road on the 23rd of March. On 13 April, 3 weeks later, I at last receive feedback. The return has been declined because I did not return the cable???? So it was lost between the pick-up-point and the warehouse, and now I cannot be refunded because of the staffs negligence. I have tried to contact them and asked that they contact me, but no luck.