MTN Increased my contract by 400% without informing me!

My current MTN contract was R200 a month. I got a notification saying my new contract is now R1400 a month for the same package (no phone included)!!!! I called in and was informed that my contract had ended and so this is my new one. How can MTN decide which contract I go on without calling me first? They forever calling promoting their packages, yet they don't call to inform me my contract is 400% more expensive. The last time my contract ended, I was given a call and they explained all the packages to me. To make matters worse, I went to MTN today (Cavendish) and the assistant said that if my contract ends, it will just continue running as is until I decide to change it, upgrade or downgrade etc. But when I spoke to someone on the phone at MTN customer service, she said that is not true.

Utterly shocked by MTN. For R1400 a month I can get the new iPhone 12 on contract.