Worst by far

I recently upgraded to 75mb line from a 20mb line. I now get less speed than what I used to get on my 20mb line, but I have to pay considerably more. so I pay more for less? how does that work. the speed is ok for maybe 3 days out of a week. by ok i mean its bearable. maybe comparable to a 40mb line. pathetic rest of the time. now they want me to pay for them to come take a look at the problem? i must pay to fix their problem.