MTN LTE coverage map misleading

I signed up a data contract with MTN as they advertised on their website that LTE offers an average speed of 7 to 20 mbps but infact that is not true. Once the contract was activated I did an internet speed test but my results came back with 2mbs download and upload speed. I logged a query with their coverage map department and was told they will have an answer for me within 10 working days. I called MTN again and was told that in my area the average speed is only 3mbs per second. So I asked them that they are advertising 7 to 20 mbps average and why am I not getting that speed? I was informed that it is area dependent but the coverage map do not show what speeds you get in what area. I requested that they cancel the contract without any penalties for false adverti*****t but they refused to. I have no other choice but to go to the CPA if they do not get this contract cancelled without any penalties.