NEVER TAKE AN MTN DATA CONTRACT

I took a data contract with MTN in 2020, the contract expired in April this year so I decided to cancel it. The call Centre told me they would take a final installment of 500 end of May and I said fine and they took it. In June they took the amount again, for what, I don't know. so I reversed the amount and now they are telling me I must pay the amount otherwise it will affect my credit rating. If anyone is thinking of taking a contract with MTN, please don't. I would advise you try Telkom not