How do you cancel an expired contract with Vodacom?

How do you cancel an expired contract with Vodacom? I advise the Vodacom shop in March that I wanted to cancel a contract on a specific number. I was told that I still needed to pay for April but that at the end of April this number would revert to pay as you go. Needless too say I now receive an sms every morning asking how I am doing to pay and I also receive a voice call every afternoon. I have been to the vodashop and the ladies, who have been truly great, have phoned on my behalf. They are sent from pillar to post and eventually on the 3rd June 2019 at 09.22 we spoke to Lita. It seems the problem is that my contract is on the M2 system and there are very few employees who know how to work with this. I was once again promised that someone will phone me back to confirm this cancellation. Lita phoned me back to advise me that some one who knows the system will call me within 30 minutes. Needless to say I am still waiting and I am being hounded to pay. What now? who knows this system, why are the staff not trained properly?