Unhappy with Vodacom service

I'm not happy with my Vodacom contract, it ended on the 1st of June 2020 but still they deducted that R304 again on the 30th of June,3 days down the line I decided to reverse that money and stopped them from going into my account because I spoke to one of their consultant around March and she reminded me that my contract is coming to an end on the 1st of June therefore she wanted to sell me something new and I refused that offer and told her that I want that account canceled after the last payment of 1st of June. But I guess it was not successful made as I asked, so now I called Vodacom on Wednesday after receiving a message saying that I owe them a sum of R529. 89 after arranging with them that I will try to pay that R304 on the 22nd of July and I hope they will cancel that account as soon as possible because I can't afford to continue paying something that ended on the 1st of June, because to me it looks like I'm paying R304 for R120 worth of airtime. Please resolve this issue for me because I even lost my job because of this Pandemic 'Covid 19'.