Complete Savings

i have just received an email from complete savings reminding me to use their membership. i was not even aware that i had this membership and on phoning up was told that i have been enrolled since 2015 when i booked on Travel Lodge. I honestly thought i was signing up for cash back and gave my details as I thought Travelodge is a credible company and not entering a paid membership and don't recall anything about reading about free trial and a monthly fee.Even though I confirmed today that I have never ever used this membership, which complete savings can prove or have seen any emails from them (which had all gone into junk presumably)they have only refunded my for the last 3 months and not the whole amount since march 2015 - £690 that has been taken out of my account since 2015! I usually dont open these kind of emails as i suspect scams and by chance i opened the one I received to day and upon calling was horrified to realize that i had been paying them for the last 3 years! I can honestly say that i have not noticed this on my statement as i only check my statements in detail if i have a problem. This is completely unfair and i would like to be refunded my money for what was essentially a false way of misinforming customers to part with their money.