dead-end vodacom

I ended my contract with Vodacom on 31 August 2020. The final bill was paid in September. Beginning of October I was billed another R574,29, Item number SCZ165642, reference ***. Going into the store, you are referred to the online number you should phone. but, the accounts enquiry is no longer valid, and phoning 082135, not one of the options relate to this. it is a stupid dead-end. there is no way to get any info and clarity. what a disgrace. the same happened to my wife when she ended her contract.