Helen was a very forgetful person, so she had placed her bank code (PIN number) on the back of her debit card. A thief stole Helen's card and was able to take $$\$ 100$$ from an ATM on the day of the theft. That same day, Helen realized that the card was gone and phoned her bank. The following morning, the thief withdrew another $$\$ 100$$. For how much, if anything, is Helen responsible? Why?