MTN providing useless internet at steep prices

I am a student at the North West University and I have been a victim of bad service from MTN for 4 years now. I started varsity 4 years ago and I took out an unlimited data contract with MTN that slows down after the use of 3GB of data. I could probably count on my 2 hands how many days in the last 4 years I have had a steady Internet supply. It hasn't been an enormous problem up until this year, I am busy with my honours degree and it is packed with assignments and dissertations which requires me to engage in constant research which I obviously require Internet for. I have had to sit on campus some night until 3-4 AM in the morning, I have had to pay additionally for Internet at Internet cafe's and I have had to sometimes borrow Internet from friends to be able to complete my assignments before the deadline. I have basically had to go out of my way to use Internet that is not my own and I am paying a couple of hundred rands a month to do so. I feel disappointed and frustrated to say the least, as if this year isn't stressful enough I have to sit with this issue.