Abuse of power from Vodacom

So last year i ordered fiber from Vodacom, the price was R675. Vodacom failed to deliver the fibre to my residence a few months later Vodacom debited R830 from my account,i called them to reverse this amount they failed to do within 7 days and i went to my bank to reverse it,after a few days vodacom reimbursed me. I called Vodacom to advise them i had already reversed at my bank and they should take their R830 but they didn't and now I'm recieving a call from VVM demanding i pay R1030.00 . Can vodacom please stop with this Harrassment.