Unprofessional and ******** contract cancellation fees.

I am on a month to month contract with MTN which I pay roughly R450 for 50minutes & 50GB data. I have noticed over the months that my data has been disappearing, I don’t use much of it as I have WiFi at the office and at home. I called today and the lady said I should cancel my contract which I gladly agreed to, but I must pay a cancellation fee of R1000. Asked her to break it down for me and she said it’s an admin fee and VAT. Bear in mind this contract excludes any device. I said the cost isn’t feasible for me as my data has also been disappearing every month and she hung up on me. I waited 20 mins before my call and was even answered and she just hung up on me.