Scam?! Charged for a subscription I never signed up for??!!

Ten months ago, I signed up to a free trial with Adobe so I could use photoshop to create some posters. I then cancelled this free trial and haven't thought about it since today, when I found out I've been charged £10 every month for ten months for a subscription plan I never signed up for, which is ridiculous. I've spent £100 for programmes I've never used since my free trial! I then tried to cancel my subsription and was charged an extra £15!! This is simply unacceptable. I spoke to one worker, who wasn't helpful and told me when the cancellation fee went through they would pay me that back, but I've done some research and I can see that something similar has happened to a lot of other customers, who have all made very angry complaints. This is simply unacceptable. I cancelled my free membership, and now I've lost ONE HUNDRED POUNDS because your site signed me up for a subscription I had no idea I was signed up for!!!