I understand that you are concerned about why your account was disabled.
The account was disabled because the card holder whose card purchased the iTunes Gift Certificates redeemed to your account has refuted the charges with his or her credit card company. The buyer will need to contact the credit card company to discuss the disputed purchase.
Please note that because your account was disabled, you will lose the ability to update applications purchased with this account.
For information about Apple's right to close customer accounts, please see the iTunes Store Terms of Sale:
Do you have a question ? These are user-to-user forums, nobody on here will be able to help with it. If you want to contact iTunes support then you could either reply to that email, or try contacting them via this page : 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