Mobile talk sold me a **** contract and took down my banking details incorrectly

Mobile talk sold me a **** LTE contract. I was told the contract was uncapped. After receiving the package I called telkom to find out it was a 5 gig day and 10 gig night package. I kept the package. There after to find out they took down my banking details incorrectly. I made cash payment and paid the extra charges there after email a cancelation form to telkom and no one has got back to me how and why are they still emailing me invoices my credit score has dropped because off this. Please help me