Send an e-mail to membersavings AT rewardsnow.co.uk stating that you confirm your phone call and wish to cancel. Print off the e-mail. Ring your credit card company customer services who's number will be on the back of yourcard and explain that you have cancelled the payment and they are not to pay rewardsnow. Tell them you have a copy of the e-mail confirming the cancellation, and if asked then post it to them. If all that fails then cancel the credit card.