Connective problems

Connectivity problems, varies by time of day.Running speed tests, long latency times up to 55ms. Sometimes disconnects from net while running speedtest. Test can take up to 1 1/2  minutes. I cannot get any response after they cancel repair ticket. This is ongoing for over two years. They know that it is not an equipment issue, hardware or wiring.Everything has been replaced. Internet disconnects between 12AM and 6AM while system is idle. Could someone put me in contact with the right unit, person to resolve this.

This has been going on for over 2 years. Frustrated in Chandler, where Cox is advertising Giga bit.

THX F101B