Cancelation of vodacom contract

I had a contract with vodacom years back around 2020 or 2021 where I took a laptop, contract was for two years,when two years was over the continued to deduct money and than what we agreed on,instead of R200 they were deducting R400.i then went to the shop to cancel which I was directed to make phone calls for cancelation which I did but the contract was never canceled

After many years when I was applying for a house to came up that am owing vodacom R565 I paid it because I wanted the process to go well.again this year it came up that am still owing vodacom R565

Am really facing a serious challenge with vodacom