I have 30 free songs on iTunes. I recently downloaded 28 songs onto my iPod Touch from the WIFI Store. When I sync the computer back up it says I still have a credit for 18 songs? I'm hoping it didn't charge the other 16 songs to my dad's credit card? I'm scared.
Try signing out and back into your iTS account. Click the Store menu (in iTunes), and select Sign Out. Repeat, but select Sign In. Your credits display should update.
Yeah I've had the same issues, I think there's an issue with the iTunes balance refresh it sometimes takes AGES to update your balance. Still email the iTunes support they will sort everything out for you.
Go into iTunes on your computer. Select Store -> View My Account and log in. Click Purchase History. It'll show what you paid for and what you got free. Click Done when you are done browsing your purchases.