ITunes

You can check your purchase history to see what you’re being billed for.

Your iApple ID email woukd have sent receipts

you might be getting billed for an app you need to cancel

To manage subscriptions and turn off Automatic Renewals, follow the instructions here:

View, change, or cancel your subscriptions - Apple Supportp

You said you have a receipt

what is it for?

i don’t understand your language to read screenshot , sorry

Contact support 

https://getsupport.apple.com/

Request a refund for an App Store or iTunes Store purchase

https://support.apple.com/en-ca/HT204084

Are you using Apple Music?

Look in your Apple ID email for iTunes receipts. If there’s a monthly charge, you’ve been getting the receipts.

Did you look to see if you have app subscriptions? Any auto renewals (most free apps aren’t really free these days)

you can do this on your phone in settings:

Go to Settings > [your name] > iTunes & App Store.

Tap your Apple ID at the top of the screen, then tap View Apple ID. You might need to sign in with your Apple ID.

Scroll to Subscriptions, then tap it.

Tap the subscription that you want to manage. ...

Use the options to manage your subscription.