Im Assuming you still have your TM Full Monty thingy, I still got my on the go, Sim Only for about £14pm, but its about to go up to £22.
Is your Sim Only Al, or are you paying for Phone included, if so, and your contract is up, you could try and blag EE to stay on your Plan but ask for some discount as the phone is now paid for (good luck with that one, but you never know).
I had a chat with Retention a few weeks back, and basically the Guy was saying (off the record) that EE want most customers with Unlimited Data off and or Upgrade to a new EE Plan, so they may come up with something on Offer.
I got offered a 4G Sim Only Data Plan with 50Gb on EE for £29, but no Mins or Txt with that, but you can pick up Mins and Txt for next to nothing these days, its the heavy Data use that gets expensive.
How much you paying at the moment? either way, if your trying to get an Upgrade Deal, dont speak to anyone other than the Retention Dept.