Overcharging my account up to R800!!

I have been battling with them since I signed a contract for my car tracker which was meant to be R200pm. To my surprise after the instalment, they took about 800 bucks from me - I luckily got that back. However, now they continue to overcharge my account even after I have downgraded to a package of R170 - The debit orders have been inconsistent. For three months I added the "on the go" product and then it was cancelled without my confirmation! On 01/04/23 they charged me R264 and On 01/05/2023 they charged my account with R300!! This month R235!! I am furious! *****ing money from me and I cannot get hold of an agent to cancel my account.