Cant get a straight answer from Comcast

Prior to the pandemic, we bought a new house and set up our 2 home offices for our businesses. Xfinity said we could NOT have 2 modems on one account and insisted we switch to Comcast Business so we could use their equipment and a Netgear modem/router. We spent nearly $400 on that unit. We were fortunate as we were able to move 100% of our businesses online due to Covid. We had nice strong uninterrupted service until 2 weeks ago and now we see the spinning wheel every few minutes. Zoom calls with patients have to be run using cellphone hotspots for any reliability. Tech support says Comcast bootfiles no longer support the Netgear C7800 modem/router (that they recommended we purchase) and they wont supply a second Comcast unit. Needless to say, our businesses are suffering. Technician comes out and says his hands are tied by corporate. Hours and hours wasted trying to reach a live person on the phone while fake robot typing sounds only annoy us further. Phone reps have ability to resolve or escalate to somebody who can. Comcast customers for 30+ years means nothing.