Vodacom - cancellation of Insurance

Cancellation of Insurance on a mobile contract. I telephoned on the number that was given to me by Vodacom. I emailed them twice on the email address that was given to me. I have not yet had a response from either the telephone call or the emails to confirm that the insurance for the contract has been cancelled. Extremely frustrating! What else should one do to cancel a contract or have someone confirm that this is indeed in progress or has been completed?