MTN taking 10 x my usual monthly payment .

AGAIN!! I have 3 MTN contracts that are 24 months, set up with Black Friday deals. The one is a data only 30Gb for R299. I have had no reminders to upgrade this contract. I went to MTN on 23rd Nov and did my upgrade as soon as the Black Friday deals came out. I also did the other 2 contracts a few days later. I am billed on the 5th of Dec R2570 for the R299 pm contract. Trying to discuss this with MTN over the phone is impossible and gets you no where. This year is a financial crisis for many people and to have companies be able to remove nearly 10 x the monthly amount is crazy. That money is desperately needed .. How can they get away with this without any legal back lash.. It would be amazing to be able to get through to someone who assist me with this at MTN , but that seems to be impossible and 2 months for general queries to be answered. Customer Service get you nowhere.