Your contract has not ended, the natural consequence of that would be your phone automatically being disconnected. You're probably thinking of your minimum-term, which is not the same thing.
EE's traditional contracts have no concept of paying off a phone, you agreed to pay your single monthly cost for at least the duration of your minimum-term, but ultimately until you give disconnection notice or explicitly request a change.
The newer FlexPay plans have two separate & independent contracts - one fixed-term finance loan for your phone, and a minimum-term rolling payment for your airtime. The finance loan here is a fixed-term contract whose payments do cease when fully repaid.
