cancellation of subscription that was never used

Good day!

I wanted to get a free trial of Adobe pdf and filled my visa card details. But payment was declined because of the long-non-use of the card. Nevertheless the system billed me for one moth. Now I cannot cancel the subscription until the card problem is solved. I havent used Adobe programme a single day. I just want to camcel it and not pay anything, because it was inaccessible to me. What should I do?

Sincerely,

unhappy subscriber