My wifi went off-line three days ago--how can I get it restored? Ready to switch providers

Last Friday, I experienced an outage. When Xfinity let me know that service was back online, I was no longer able to access wifi. 
Since Friday, I have tried to receive help from the "Assistant" which is incredibly limited and frustrating. I've texted with multiple techs and, when I've lucked into it, I've spoken on the phone at least one tech, maybe two.

It's now Monday. I just had another hour-long session with two techs who seemed to be doing their best to try to help, but I'm still without wifi. Oh, and I took my Gateway modem back to the Xfinity store, where I was issued a new one. Same problems.

My husband and I have spent no fewer than 10-12 hours over the weekend and today trying to get help troubleshooting this problem. Now, we've been told that an in-person technician has been scheduled to come to our house on Thursday--earliest appointment available. By Thursday, it will be a week without wifi. Unacceptable!

The problem? Here's what it looks like to me: Xfinity says that we can use a customer-provided router with the Gateway when bridge mode is on. This is how we've been successfully operating for 6 months. On Friday, when service was restored, we suddenly became unable to operate with our router (using the Xfinity Gateway in bridge mode). We've replaced both the modem (Gateway from Xfinity) and router (probably didn't have to purchase a new one since nothing has changed). No wifi.

It appears that Xfinity is trying to eliminate our ability to use our own router so that we are forced into renting Xfinity extenders. It's a racket!

Our wifi was working fine before the outage Friday. After the outage, not working. WHAT CHANGED????? New protocols that limit our router's ability to receive a signal from Xfinity's Gateway?

The automated assistant is worthless and frustrating. The chat agents are trying but unable to resolve it. The phone agents are nearly impossible to get to, and are largely unhelpful. I have to wait until Thursday for an in-person tech, and I'm not hopeful.

My only real option is to find a new provider.