I signed up for a data bundle that would quadruple after 12 months??

I've been a loyal Mtn client for over 12 years and i was shocked to the core this morning. I've been cheated into a contract that quadrupled in price after 12 months. It is unreasonable and totally irrational for anyone to agree to a 4x price increase after 12 months. So why did i agree to something like this? I DIDN'T. Your salesperson failed to disclose information that would have resulted in me opting out of this data contract. I feel cheated, i'm angry and i would like someone from Mtn to resolve this.

Why in God's name would I agree to a contract than spikes from R200 for 2GB of mobile data to R800 after 12 months! I wouldn't especially when I specifically took out a contract that was considerably cheaper than my previous 2 upgrades! I needed to save money and if i had the information i required to make an informed decision i wouldn't have been stupid enough to agree to those conditions!