Afrihost charging me for a 20/20 line yet only receiving 10/10

I have been struggling to get the speed that I have been paying for, I upgraded from a 10/2mbps to a 20/20mbps yet I only had that speed for 2-3 days, since then it has dropped and remained 10/10, yet I am paying R907p/m for the 20/20mbps. I tried for 4 days to get hold of them without success, after a week I tried again and managed to get hold of them on WhatsApp, they told me to reboot which I already had done and told me to take a screen shot which I did and proved to them it was 10/10, they said they would escalate to technical dept and having heard nothing since a week ago. In those 7 days I tested everyday and only once for a part of that day it was at 20/20. I cannot continue to struggle like this as I am self employed, my wife an estate agent and we hok me school our children, so having constant reliability is important to us. My account no. is A***7 and my cell no. ***, email *** if this is not resolved soon I am going to have to approach another service provider and I need to be credited.