Horrid mistreatment of customers that should not go unaddressed

I returned their router and power cable after cancelling my fibre service with them. I personally delivered the required device to the premises specified by WebAfrica, on 29 May 2023 AND received written confirmation that the device had been received after personally witnessing the consultant log it into the system. About 2-3 months later, WebAfrica are somehow of the impression that I have never returned the device, trying to debit my customer account for the price of the router and when I queried this with them (providing written evidence for the device having been returned) they are now telling me they need a 'waybill in order to investigate'. The list of problems with this treatment is shocking to say the least. I am hoping WebAfrica can learn from this - speedily - and IMMEDIATELY STOP trying to deduct funds from me for a device they would know they already have if their record keeping was as meticulous as their attempts at debt collection - in this case a debt THAT IS NOT EVEN OWED TO THEM