Hi
To see past purchases via your iPad, follow the steps here:
Download your past purchases - Apple Support
If you have access to a computer, you can instead follow these steps:
See your purchase history in the iTunes Store on a Mac or PC - Apple Support
If you did not authorise the payment - and if it was not made by a family member under Family Sharing - options include:
To ask Apple if you can cancel any given purchase and receive a refund, go the following page and click on Report a Problem next to the purchase:
Contact iTunes Support for assistance:
If you believe that your Apple ID may have been compromised, follow the steps here:
Note that no-one here can access your account or issue a refund. You are not talking to Apple here - this is a user-based support community.