Apple charging monthly installments on a iPad edu gift card

The following links should help you to both identify and manage any recurring Apple service subscriptions associated with your AppleID account:

If you want to cancel a subscription from Apple - Apple Support

Manage App Store purchases, subscriptions, settings, and restrictions on iPad - Apple Support

Subscriptions and Billing - Official Apple Support

View your purchase history for the App Store, iTunes Store, and other Apple media services - Apple Support

If you are unable to identify and resolve the unexpected charges from Apple, you would be best advised to seek assistance directly from Apple Support. You can contact the Support Team using the Support link at top-right or bottom-left of this page. Alternatively, you can initiate and manage your support cases from Apple devices using the excellent Apple Support App. If not already installed, the App can be downloaded from the App Store:

https://apps.apple.com/app/apple-support/id1130498044

no idea

if it was me then I would check if the appleId had active subscriptions and if so cancel them read

If you want to cancel a subscription from Apple - Apple Support

and maybe read

If you see 'apple.com/bill' on your billing statement - Apple Support