Thanks, Maria. The problem with supporting fora like this is the users will share information - so, the supporting group/commercial entity needs to have sufficiently good enough products to ensure everyone, in the end, provides comments relating to a positive experience. There will always be outliers with unfair stories - that is not the intent of this thread.
Here is the update from today ... after a couple hours on the phone and a visit to the local Cox store to return the ETM box (has the ability to support landlines), the used modem I had was turned on and I'm up and operating. Our newly negotiated cost is not yet shown online, so will withhold statement until I see it with my own eyes.
The ETM box is a bit special compared to the usual cable modems ... it has ports for RJ45 phone connectors, which are not needed if you don't have a land line. Since I had a land line and wanted to disconnect it, I had to go through the turn in dance, followed by the turn on dance (tried in person, but they couldn't do it, so had to call). The SB6212 (187Mbps) modem works great at over 100mps, so that part is good.
My sense is that Cox and all the telecoms will continue to have differential pricing that once you sign up, always goes up ... then, when you complain, they negotiate to keep you ... then when you have had it and quit, they price their products fairly and you come back. Much like being on a 200 person airliner, everyone up and down you street pays a different price for getting there. I wish they would stop this, because it is bad for loyalty and collaboration, but if they did then other, more competitive companies would not have an opening to steal those customers away with a better product and service.