Vodacom contract is nonsense

I took a 24 month contract 2020 (RED Huawei Y60 + 50Min + 650MB) paying R200 then it went up R240 until I lost income +- 8 left on the contract, I them resume paying for few month until I received last invoice with 0 balance. I contacted customer care to cancel the contract as advised by a consultant only to be told I still have 6 month left. but the lady says I am no longer paying for the device as I am done but I will be paying for the data and minutes that I am receiving .my problem is the amount payable did not drop I am still paying R230/240 whilst they have excluded the device and its only 650mb and 50 minutes for that amount.