Internet either down or loading slow

This problem has been happening for four months. There have been days in a row with no internet at all and days where the service goes down in the evening for hours or where the internet is on, off, with erratic access. I have spoken with CS and two times there were protracted outages. I was sick of the problem, so I read an Att a Uverse brochure and went online to find out about switching and their service was down! My once reliable service has become so highly unreliable I don't know what go do.