Rain worst customer service and incorrect billing

Horrible service.. Horrible service, this is my billing cycle below. U pay for the service in advance I cancelled for end of Aug and they deactivated my sim end of August and billed me for September and I ask them why and the say the September debit is for the service consumed in August. I am trying to explain on the email that no you are billing me incorrectly because I have already paid for Aug end of September and you were not supposed to debit post end of Sep. Falling to dead ears and their call centre number Is not functioning due to covid, what an excuse. This is what I call *****ing, *********** agents

Date Type Amount 31 August 2020 MonthlyDebit R479.00 31 July 2020 MonthlyDebit R479.00 30 June 2020 MonthlyDebit R447.06 31 May 2020 MonthlyDebit R0.00 28 May 2020 R479.00