PDFSimpli Processes Unauthorized $55 Charge After Canceled Subscription

I would like to report an unfair charge I experienced regarding the service I received through PDFSimpli. I previously canceled my subscription on the site through my account; it gave an error on my first attempt, but when I checked again, I saw that the cancellation had been completed successfully. Despite this, a single charge of $55 was processed from my card on June 27th, and I noticed that my subscription was reactivated in my account. Upon seeing this, I canceled my subscription once again.

I have not contacted customer service regarding this transaction so far. I do not accept being charged despite having previously canceled my subscription on the website, and I demand a full refund of the $51 payment along with the permanent closure of my subscription.