I Need Confirmation That My Simple Weight Loss Subscription Is Canceled

I registered for a Simple Weight Loss Program subscription around February. Shortly after signing up, I believed I had cancelled the program in March. I did not receive any response or confirmation from the company regarding this cancellation, and I have since been unable to access my account in the app to verify my status. Despite thinking I had cancelled, a charge of 72 USD was taken from my Visa card on March 25, which I do not remember authorizing, especially considering the high amount. Because I cannot log in to my account, I cannot check what plan I am supposedly on or why this payment was taken. I request clear written confirmation from the company that my membership has been fully cancelled and that no further charges will be made to my Visa card. I would also like clarification regarding the 72 USD charge on March 25, including what it was for and whether any further automatic payments are scheduled, so that I can be sure this subscription will not continue.