Reinstatement of cancelled contract

We accepted a contract from a Telemarketer, but then decided to cancel the contract, which Vodacom did (they even called to confirm it was cancelled). On their system it is noted that the cancellation went through. However, the contract was reinstated after the cancellation and we do not know why. After calling Vodacom they stated that they needed to do an investigation, after two weeks of waiting we called with the reference number but there was no record of it!