Don't know what they are doing

Paid all the outstanding money but for some reason they are still billing me for R5000 for the device's how the hell did we get there? I wanted to continue to use the contracts and now for the second time the no is deleted. There's no way i'm paying for new simcards and reactivation fees again for a stuff up the accounts department made. They can listen to their own recordings and see that the fault is made by their own people. I spoke to yhem over 3hours just to have them stuff it up again