Reverse my money, i'm no longer using your product

On the 19th of April i returned a nupay machine, i met a guy at Tarataalrand he gave me a form to sign. On the 1st of may nupay deducted R983,25. I called a sales manager he didn't answer my call, i wrote a message to him to ask him to cancel a debit order. This evening again 4th of June they deducted R983,25 what for? I'm not using your webfin system and your machine since 15th 0f April, so why are you still taking my money? Debtors account no:*** reverse my money please.