Files Editor Charge and Cancellation Issue

I subscribed to a PDF editor service called PDFBILLINGCOM MI through the Apple App Store, and although I have never used the app, I am unable to unsubscribe from my side. On 10 September 2026 an amount of R945 was deducted from my account as a subscription payment. When I go into my iPhone Settings and try to access the Subscriptions section in order to cancel, the Subscriptions page does not open and I cannot proceed with the cancellation. Because of this technical issue, I have no way to manage or stop the subscription, and my last available funds were taken without my active consent. I request a full refund of the R945 taken on 10 September 2026 and an immediate cancellation of any current and future subscriptions or charges related to PDFBILLINGCOM MI. I would like written confirmation that the subscription has been terminated and that no further deductions will be made.