Why does Xfinity not honor new customer promotions with existing customers?

Why does xfinity not allow current customers who are out of their contract to take advantage of new customer pricing when it had a 1 or 2 year commitment agreed to? I am incredibly frustrated with the chat "agents" that keep disconnecting themselves from chat when i ask why i cant even view offers in my area as a current customer. Its not a matter of signing up a new customer to add to the xfinity service, its a matter of losing a customer that has been with you for decades.