Unfortunately there's nothing you can say that will change the way they handle the issue. They will connect directly at the tap and test for packet loss. If they see packet loss, they open a ticket to have higher level maintenance fix the issue. If they don't see packet loss, they will say the problem is with your cabling or equipment. Your connection looks pretty bad so it seems likely they will be able to see a problem at the tap if one exists.
Also while cable modems very rarely go bad, yours is using an older technology. Replacing your cable modem with a new DOCSIS 3.1 modem such as an SB8200 won't fix your current issue but it will help you to have a better experience overall.
How much of a difference DOCSIS 3.1 makes on slower speed plans is baesd on the level of congestion on the node. DOCSIS 3.1 allows for more QAM channels and also for OFDM which can carry a lot more data. It's also good to keep your modem current because it makes it harder for Cox to blame the modem. Anyone who subscribes to cable internet should basically budget to buy a new modem every 4 years or so, just to keep up with technology. Same as anything else. If you keep up with technology you have a better experience.