Vodacom robbing me monthly and I can't stop it

I've been a Vodacom customer for 20 years and the service fee by debit order is usually R430 a month. In November 2023 they started taking R2400 per month. No upgrade, no new phone, no increase in the calls I make. Just started robbing me monthly. I only noticed in April 2024 and reported the problem as "upgrade *****" (a thing, I assume). Sent them IDs and proofs and statements and explanations as required on the same day and was told I'd be contacted within a day or two and the problem would be resolved within a week. Well guess what? Crickets. Every 2 days I get a reference number from them by text. The same reference number again and again ... calling doesn't help, I get blah blah yes we'll sort it out and then nothing happens. Its now the end of another month and they're going to ***** another 2400 from me. ******** disregard for, and abuse of, their customers.