Unable to view or Change plans, Compare Plans, Offers and Packages

Why are Comcast/Xfinity existing customers unable to view different packages, deals or offers? When signed into their Comcast account when clicking on top "Change Plans" via Comcast/Xfinity's website and app, you receive an error message, Sorry, please call. Normally any consumer is able to view, review, compare offers, packages and deals prior to purchase of anything or signing of a contract. I cannot compare my existing plan to any of your other offers, different plans prior to my 12 or 24 month contract expiration date. If I am looking to modify my plan, update, change it and/or look at deals before my promotion is almost up with you, and my contract is about to end or expire. When I click on the "Change Plan" link in the XFINITY App or on the XFINITY website it loads "We're Sorry" Please contact us and one of our friendly and knowledgeable representatives can help, site (https://www.xfinity.com/error/buy/sorry?errorCode=plan-contact-us) I have called in repeatedly about this and have been given countless different reasons several calls, contracts and years later as to why your existing customers can't simply view them. Doesn't seem like there's any appreciation at all for your existing customers nor customers who've been with you for years. This continues to be an ongoing issue and unless you are a new Comcast/Xfinity customer there doesn't seem to be any appreciation. For example, why is it a package you offer your existing customers who have been with you years are always much higher than your new customers, $149.99, $159.99, $169.99, $199.00? For your new customers packages are much less, $129.99, $109.99, $99.99,and lower etc. Another example, for your existing customer sign up for 24 month packages. That 24 mons is broken down and listed on contract as 1-12 mon at one price, then that same package is increased even more 12-24 mons. Thank you.