Bill increased from $45 to $85 — discrepancy with advertised 5-year promotion

Hello,

My one-year promotional rate recently expired, and my monthly bill for 500 Mbps internet increased from $45 to $85. I contacted customer service, but the only alternative offered was to downgrade to 300 Mbps for $70/month, which still seems too expensive.

When browsing Xfinity's website, I found an offer for 1 Gbps internet with a five-year price guarantee advertised at $65/month. However, when I select the offer and proceed through checkout, the price changes to $75/month.

I'd appreciate help clarifying a few things:

• Why does the advertised $65/month price change to $75/month during checkout?

• Is this five-year promotion available to existing customers?

• What is the best available rate for my account for either 500 Mbps or 1 Gbps?

I'd prefer to stay with Xfinity, but I don't think $85/month for my current service is reasonable, and the downgrade offer doesn't provide enough savings.

Thank you for your help.