Intellicell.co.za refusing to cancel the contract

Don't ever take any contract with them. They'll refuse to cancel the contract. My contract ended in April. In May they created a debi check and deducted. I told them to cancel the contract. In June they still debited my account. I told them in June to cancel the contract. They told me the contract was canceled after paying for 2 months even when the contract has ended. Now it's August they debited this month. I reversed the transaction. After then they threatened to ruin my credit record.