Paying

If the app had an auto-renewing subscription just deleting the app won't stop it, that only deletes the app. To stop a subscription : View, change, or cancel your subscriptions - Apple Support

Purchases are considered final as you know, but you could try the 'report a problem' page to contact iTunes Support and see if they will refund you as a one-off : http://reportaproblem.apple.com

Or you can try contacting iTunes Support via : http://www.apple.com/support/itunes/ww (click on your country's flag, the country where you live, and which is therefore the country on the account ; click on Contact Support towards the top right ; click on Get Help under 'Talk To Us’)

I can't do that, I'm just a fellow user. See my previous reply and try contacting iTunes Support.