I'm thinking of throwing away a customer's credit card
I hope that's not going to happen. Wy would you throw you card away?
I found out, her credit card expired on the 21st at least put a notice up
I understand, but you shouldn't just throw out a customer's credit card without asking. You should try and contact the customer first.
She doesn't deserve my help.
Don't you think it's not her fault that her card got lost, what if yours suddenly disappeared? Even though it's out of date, why not keep it safe within the company? Your coworkers would be inspired that you'd do the right thing!