Cancellation of process of debt review and debit order.

I got a call from DebtCo Group CapeTown. Tellin me they can reduce my car installment. My instinct was tellin me otherwise bcos i can afford this payment. I have since asked them to cancel the process but the people who were calling me now are not available. Can i get assistance in clearing this before they start debting or giving me a bad name for credit.