Bad Sercvices

I have cancelled my contract with this company and Our initial contract was to debit an amount of R8000. Now they debited an amount of R19000. When I contact my bank they said they cannot reverse it I must speak to my service provide. I called NDA I spoke to Lavona. She advise me to go back to my bank and ask them to reverse but my bank cannot reverse they refer me back to the services provider which is not helpful either