Overcharged on contract

Good day, I signed a contract with vodacom at Vodacom Woodmead on the 1 st of february 2020 for Huawei P30 lite *2 which was on promotion which was supposed to be R 550 PM*24 but now ever since i am paying 629 PM. I went to the store they said there included R 69 for SIM which they were not supposed to so the escalated the issue to Vodacom support and sent me reference number. Few day later i received SMS stating that my reference number is closed. Today i contacted customer care to ask why my query was not attended yet closed the consultant told me that the change was suppose to be done by Vodacom Woodmead in the beginning of the contract so they can't change it now. Then i requested a quote of cancellation , they sent the quote but i was also unhappy because they included the airtime and data which i dont want anymore. When i was inquiring about the quote they said i am on arrears so they wont discuss anything with me i must contact collection department but they debit every month.