Trying to upgrade my plan to unlimited, won't let me unless I upgrade my modem

I currently have the gigabit plan and I own my own modem at Netgear CM1000...it's working just fine. I am trying to upgrade to the unlimited plan "you'll need new internet equipment for xFi Complete".

Why do I need new equipment to get the same service that I'm already getting, just unlimited access? Why am I being charged for a "getting started delivery kit". Do I not even need this stuff and am I worrying for nothing?

And my shipping address does not match my service address so even if I ordered the kit I wouldn't get it. I can't find a phone number to contact xfinity anywhere on your website, can you please provide me with a means to call in for help? Thank you.