Purchase An Item I Didn't Mean To Now It's Charging Me Every Month On My Debit Card

If you are being charged then it's probably an auto-renewing subscription (deleting an app doesn't stop its subscription) - in which case there are instructions on this page for managing and stopping them : http://support.apple.com/kb/HT4098

For what you've already been charged, purchases are considered final but you could try contacting iTunes Support and see if they will refund or credit you : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page, then Purchases, Billing & Redemption