My Time Rewards — Unethical behaviour

I was shopping online with Simply Be clothing shop, as a first time buyer. I paid and everything was fine, a box appeared saying to get £15 off your next purchase, click here. I did so, and it said that we need your credit card details, which is the point I should have suspected something. However, I am not gullible and i suspect many other people would do the same. It was only after they had my card details did they say who they were - My time rewards. I knew nothing about them and certainly did not want to pay them £10 a month for whatever they offer. As soon as i realised, i phoned Barclaycard to stop this company taking my money, and they told me it would be better to cancel my card, which is what i did. I wrote to Simply Be, who host this company, but all they said was clear and i should have contact ed My time rewards to cancel. I did not trust them, so i did not want to do that. It is not direct fraud, but it is very close to it.