Poor service

Asking for a technician to come out and see why our line speed is not 100mb/S, but a max of 35mb/S, I have asked many times for a technician to come out and see what is the cause as I have told them before that it is the rooter giving problems, all I get back after requesting that a technician must come out, is that they will send it to the relevant department, but nothing happens, as this is now the 3rd month that I am paying R899.00 for a 100mb/S line but in fact that the line has a max line speed of 35mb/S, which I do not understand, as soon as I am able to talk to someone, they run a speed test and they confirm the line speed is 100mb/S, and they then do changes to the rooter, but as far as I know, that when you start to change and keep on changing settings on the rooter, over time the speed and function will be influenced, that it will no longer work 100%, Soni am asking again, please phone me on ***, and discuss that a technician be send out to our house ASAP, thank you