Latency Variation. Unstable Ping. Intermittent Connectivity.

At this point I do not know what to do anymore. I'm on the brink of switching to another provider but I don't want to lose my home telephone number.

My ping used to be stable up until a year ago, I literally had the lowest ping, it never even moved or had any jitter. Now it's spiking every second dramatically. You can't play games and it even causes regular PC and TV usage problems.

There's literally nothing I have not tried.

I have the ethernet connected to my PC.
The problem occurs throughout all the devices, wired and wireless so clearly its not a matter of my personal devices.
All the ping tests I've done show graphs that are jumping up and down.
I tried bypassing the router which didn't work.
I tried changing the BTU size and that failed.
I changed the IP address
Got a new modem that failed
I've done a cmd ping test on like every address and it the ms ranges from like 15-230!
Got a new router that failed
It doesn't matter if its night or day or 3 am at night, the ping is unstable and the jitter is off the charts.
It doesn't matter if there is one device using the internet or 10.
I contacted Cox about 5 times by now, and half the time there technician won't send in the reports or submit the requests for people to come fix the issue.
Cox has replaced the internet line but not the port and that seems to be the issue.
The first tech came, ran a test on the port and showed me his device which showed failing statuses. He said a third party guy will come to replace the port. No one ever came and instead Cox sent a regular tech guy and he didn't know what he was doing and left. Later on another tech guy came and tested the port but this time it was all in the green...