a VPN App Subscription not attached through Apple store payment.

Hi There,

In order to entitle for free trail i opened shurfshark app and used my yahoo account for sign up for 1 month free trail and setup a mandate which is refundable the app says.

later while I login with my yahoo ID, the login do not show any subscrption attached. The VPN App Tech support said I should use the apple ID to login from which payment was made, so later I used apple ID even that also did not work.This app is accepting money and unlimited email addresses and not able to link subscriptions . My fear is even in APP store in purchase history the receipt not show however money got deducted also Im afraid of recursive payment withour my intention. The customer support says 30 days money guarantee could not even locate my details at all either of my email sign in's. I 'd like to know the process to revert the transation from App store side.

Thank You,

Chandra