Modem not getting upgraded speed after changing to a faster plan

-----This has been resolved-----  Thank you XfinityOrlandoM for you help!

I made changes to my services that included moving my internet from an old legacy 105 mbps plan to a current 300mbps plan. My customer owned modem restarted during the upgrade process, but it has not picked up the new speed even after several power cycles, restarts, and a factory reset. A speedtest shows exactly the same speed I was getting before. My modem is a Motorola MB8611 which is shown as being compatible with the 300 mbps speed plan. I tried investigating this issue through the assistant chat, and was told there are multiple modems showing on my account. When I look at my account online, I only see my current modem listed. I'm concerned that the provisioning for the new speed might be getting directed to an old modem that no longer exists instead of the current one. I am connected and internet is working, but at the old plans speed, not the new. I could not get the assistant chat to understand any of my questions about this. Any suggestions? Is there a way I can verify that the provisioning of the new plan speed is getting sent to the correct modem?

Thanks