MTN not providing what was stated in their contracts!!

I have a month to month internet contract with MTN. According to the contract I have a 10mb line speed with a cap of 100Gb per month. Once this cap is reached, according to the contract I signed the line speed is dropped down to 2mb. So for the first time since I started this contract I reached the cap on the last day of the month. My line speed has been dropped to 17KB which I have proof of after doing a speed test and taken photos thereof. So MTN is in breach of contract. To any reading this, do not use MTN as your service provider as this is not the only issue I have had with them. DO NOT USE MTN FOR INTERNET AS THEIR CONTRACTS ARE A LIE!