Cheers mate! Do i sent the letter to harlands or exercise for less?

I cancelled my direct debit, a few weeks ago to exercise for less because the 12 months was up about 3 months ago. I didn't think anything of it, i thought it ended after 12 months but i was still paying i don't even go anymore. Today i got a letter from Harland's, wanting me to call them to reinstate my direct debit and charge me £34.99, even though membership is £10. Ive just cancelled my membership on exercise for less website, i didn't know that you could do that or i would have in the first place. I don't want to pay 34.99, ive payed it before when ive missed a payment, its such bull****! So i did some googling and found this forum, please help!