CELL C NOT CANCELLING CONTRACTS

Very poor service. Good luck to any one who can get their contract cancelled. Every time you call to cancel contract they "CAN'T VERIFY YOUR CREDENTIALS" or "YOU FAILED THE SECURITY CHECK" and when I chose UPGRADE I PASS the very same Security Questions?!! How is it possible. They have successfully delayed me for 10 months in cancelling my contract. I recorded all my calls today, proving that the security questions are correct and passed for all queries/upgrades except for when wanting to cancel.