Billing/retention issue

My promotional rate recently expired, and my 500 Mbps Internet price nearly doubled from $35/month to $65/month.

Before the promotional rate expired, I contacted Xfinity through online chat specifically to ask about the upcoming price increase. The agent told me that my $35/month rate had been extended for another 12 months. However, the $35 rate only appeared on the following month's bill and then my price went back to $65/month.

I subsequently contacted Xfinity again through chat. The second agent told me that the $35 rate could not be extended for another year and that the previous agent must have been mistaken.

I'm hoping someone can review the prior interaction and my account notes to see what happened. I also see Xfinity currently advertising 500 Mbps for $45/month with a 5-year price guarantee for new customers. I understand that offer is aimed at new customers, but I'd like to stay with Xfinity if there is a comparable retention or loyalty offer available for my existing account.

Could an Xfinity representative please review my account and let me know what options are available? Ideally, I'd like either to have the previously communicated $35/month extension honored or receive a comparable retention/loyalty offer at $45/month for 500 Mbps with the same 5-year price guarantee currently available to new customers.