Multichoice overcharging customers

I know longer know what to do. Multichoice has done it again. I have been billed twice and I paid my instalment. I am on pricelock and I made them aware that I' ve changed my bank account and the previous account they were deducting from money was reflecting late. I paid my account cash on the 22/07/2021 and I paid extra R77.00 because a consultant said its areas ok I was fine with it. After I checked my balance and it was on standard I have proof of that. After a day I received a message that I have to pay an extra R436. Yesterday I checked my balance again it shows R975.00. I need help with this account really this is due light roberry.