Unauthorized $3.96 Monthly Charge From ThePDFGuru.com on Chase Credit Card

I have been charged by THEPDFGURU.COM, Dover, DE, on my Chase credit card every month with an amount of 3.96 USD, even though I never knowingly signed up for any paid subscription with this service. The first charge that I noticed dates back to December 2014, and these payments have continued monthly up to the present. I did not authorize a recurring subscription with THEPDFGURU.COM and was not clearly informed that I would be billed 3.96 USD every month. I only recently realized that these small amounts have been taken regularly from my Chase credit card for years without my informed consent. I request the immediate cancellation of any subscription or recurring payment connected to my name and my Chase credit card with THEPDFGURU.COM, and I also request a refund of the most recent charges that have been taken without my clear approval. I expect this issue to be investigated and resolved promptly, and I would like written confirmation that the subscription has been fully cancelled and the recent payments have been refunded.