If you keep your credit card number on file for easy checkout for online retailers, the number may have already been there on the computer.
Never do this! It is better to type in the card number every time.
Loved the fact that you unplugged her. We did this once for our son at age 12 because of a bad report card. The grades came up really quickly.
Also like the idea of the kid having to work off the debt for minimum wage. At $7.25 an hour it would take 69 hours to work off a $500 debt.