If you have missed your contract end date and cost has increased due to losing discount then that is number to see what BT will offer you to renew contract. If not what you want you don't accept and if out of fixed contract you can move without cancellation fees
First of all you need to go to this page. https://www.bt.com/appsordermgmt/secure/listoforders.do
Then select the order that you wish to view, and on the top right there will be a link saying "Show contract terms"