Cannot Cancel Shortmax Subscription Despite Correct UID Details

I have been trying to cancel my Shortmax subscription for about three weeks and have not been able to do so despite several attempts. I first tried to cancel through the app, then through the subscription settings on my phone, and finally by emailing Shortmax directly. In their email replies they asked me for information such as a UID number and other account details. I provided everything they requested and even copied and pasted the UID exactly as shown, but they repeatedly replied that the information was wrong and that they could not find my account. I also tried using the email address and phone number I signed up with, but this has still not resolved the issue. Despite all these attempts, my subscription remains active and I am not able to cancel it. I request that my Shortmax subscription be canceled immediately and that written confirmation of the cancellation be sent to me as soon as possible.