I was quoted one price then told another

​I just moved to a new place and have been trying to get my Xfinity to activate over there. While discussing over the chat I was told I could upgrade to 1200mbps unlimited for $85 a month for 24 month contract. I waited 3 hours and my internet was never activated and when I checked in with chat I was told there was a system glitch and I had to talk to someone on the phone. When I talked to someone on the phone they told me it was going to be $100 and didn’t give me much more information, just kept saying I currently had 1000mbps and if I wanted to upgrade it would have to be after a tech came out and there wasn’t a deal with $85. I took screenshots of the entire convo and even signed a order to confirm my new order of 1200mbps.​

​This all took place within 8 hours. What is going on?​