I know the feeling. I opted to drop DSL when our modem started to fail. So I went with fiber. It worked, but the phone line quit. after waiting 2 weeks, the company came out and seems the installer failed to connect the phone to the fiber and the install was poorly done by the company so they would fix it. We went out of town, came home July 4. Neither the phone or the fiber worked. I spent long hours over the next 2 weeks on the cell phone, listening to dork music and reminders it would be quicker to go chat on the internet, but no way to connect. Finally someone came out, same company. he did some stuff outside, then disappeared to come back and said, "at the junction box down the street, someone from our company disconnected your line and other lines, soI connected you and the others back up, put in a note there, and your install is shitty and I will put in a repair ticket.
So we have the fiber, the phone and still the shitty install. Now when I see the centurylink truck in the area, I want to run to them and tell them not to screw with my service. I would have gone with Mediacom,but they are bad too. So I have DirectTv and fiber, almost a gig both ways.
Keep after them