Lower download speeds costs More for renewal

I went online to check the plans available for us. I was using Blast Internet only and my bill was $89.95/mo. I could only find a "cheaper" plan by going UP to Gigabit service and paying $85.00. We are only two septuagenarians who only use internet and our own modem. 400Mpbs is more than enough for us and our needs, BUT, if I downgrade to that it will cost us MORE according to the plan page, $95/mo. Frontier fiber became available here just recently at $49.99/mo for 500Mbps. Before we consider a switch, is there a better plan we can stay at Comcast? We use both Internet and Xfinity Mobile and are long time customers. Thank you