refund on vodacom account

On end of JUNE I changed my banking details, Vodacom did not change my details. I made a cash payment at a vodacom shop. I made another phonecall to vodacom. banking details were not changed yet. T his time i could do it over the phone. August they deducted a double payment from my account. Up to know that manual payment do not reflict on my account. After three log complains,nothing is sorted out. My grand daughter of 11 can do a better job as the retarted people working at vodacom. They refuse to give me a refund