CONSTANT service interruptions on a daily basis. I

I have had nonstop issues with my internet disconnecting and reconnecting. There is CONSTANT service interruptions on a daily basis. I have followed all the troubleshooting steps and now I am being told they are going to charge me $75 to have someone take a look at the issue or I can upgrade my modem...I am one person, using one device at a time on WiFi with a modem directly behind me. Anyone have any real advice or should I cut my loses and run?