I was also duped into a free trial of HighCreditScore who claimed to be affiliated with Skipton Building Society, so it felt safe. When signing up, the forms continued to a second set of forms which appeared to be a continuation of the same, but it was in fact RewardsNow. I received two e-mails with lots of text, and in the middle of it were the costs. Shock horror, £19 per month for one and £15 for the other. I immediately followed the instructions to cancel. Highcreditscore sent an e-mail to confirm, Rewardsnow did not.
I signed in to the sites and there are screens to cancel. You have to surf around a bit to find them. The Highcreditscore presented a yes/no choice with no obvious answer displayed to what they meant. I selected the no which was the right choice as the yes was in fact do not cancel. The rewardsnow was clearer and displayed a message that an e-mail was sent, but it was not received. In both cases I made a screenshot of the confirmation, and saved them for my credit card company.
I telephoned Highcreditscore and confirmed cancellation, and rewardsnow and followed their instructions.
I sent an e-mail to the sending e-mail for rewardsnow, but they were invalid. I sent another to the e-mails for canellation provided, and copied to both Highcreditscore and rewardsnow. I received replies to my spam confirming cancellation.
All the replies were prefectly professional and imply that I have been successful.
I called my credit card company and blocked payments, and complained to the Skipton Building Society.
I hope it has worked, but interestingly I have now started receiving a string of phishing e-mails requesting my banking details. I believe it is no coincidence.