Vodacom - Cancellation (Spiteful Behaviour)

I have a contract coming to an end in July. Cancelled in May already for the end of my contract period. Since the cancellation Vodacom started billing me higher amounts than the stipulated contract values.

I have opened a complaint about this on 3 occasions now, to which I am not even contacted back, and retention department just closes the query and marks it as resolved, with no opportunity for me to dispute.

The only communication is an SMS that tells me my discounted rates ended in May (When I cancelled the contract for the end of contract period)

As far as contract law goes, Vodacom is not adhering to the contract terms which nullifies the contract as far as I am concerned.

I have given Vodacom every opportunity to contact me, there is one lonely customer care consultant who is helping me, but retention dept just assist blocks her and me the same.

I feel sorry for people who have to work for an employer like this who are ruthless and immoral in their trade practices.

Prove me wrong.

Relating to data contract ***