Vodacom is useless

Vodacom sent me a bill of R987.63 on 6 July 2025. I logged a query because my bill ranges between R507 and R560 monthly. The guy who assisted me said instead of them deducting the discount, they have added it to my son’s bill. He said we should give them 10 days to resolve. On 31 July I spoke to *****bo inquiring about the status of my logged query, she said it was resolved and on 01 August 2025 Vodacom will deduct my usual amount. To my surprise, Vodacom debited R774,75 from my account. Where does this R774,75 come from??