I had a $15 itunes card. I brought 2 songs for $1.29. It shows that my balance is $4.70?

You've checked the purchase history on your account, as per the HT2727 page that you posted from e.g. you didn't have any auto-renewing subscriptons or pre-orders that were due ?

If not then have you tried logging out of your iTunes account on the computer/device that you are using and seeing if it shows the correct amount when you log back in ?

If not then you could try contacting iTunes Support and see if they know where the rest went : 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