MTN Black Friday contract expired - Bill shock

My MTN Black Friday contract expired 2 days ago, now I find out they charging me R1800pm when I was paying R330pm. Their new black Friday deals are not even out yet which I was waiting for to upgrade too.

I called CS to cancel my contract immediately, she said im still liable to pay the R1800, even though its 2 days in the new billing cycle.. also if I upgrade now, new fee will only be after the R1800. I dont have this money and want to cancel this with immediate effect, I don't mind paying pro rata for the 2days.

Also in no way did I agree to this new amount monthly contract... Something needs to be done to these SP's... whats stopping them from making the new fee R500k pm? HUH we just have to pay it???