Vodacom is charging me for something I don’t have

Last year (2017) August, I requested Vodacom for an upgrade online and it was approved and the handset was delivered by Ram, after a few weeks I called them to notifying them that I won’t be needing the handset anymore and they said they wil organize for the handset to be collected and it was collected by Ram and I have proof. In December Vodacom charged me for the handset that I returned back to them and I reversed the money hoping maybe they will call me to discuss the payment and they never did. Then I phoned them asking for clarity and only to find out I’m being charged for the handset that I don’t even have in my position yet I put a complain again early last year about their network in my area, up until today nothing has been done about it. I’m seriously considering changing my mobile network to the company that will be able to cover my needs as a customer.