
Quoting
cbg
You can face both civil and criminal fines. I'm assuming that what you're looking at is the civil demand. You haven't told us how much you stole, but the civil demand can't exceed $500 over that amount. So if you stole $60 worth of goods, the maximum civil demand is going to be $560.
But you can also be criminally charged. The fact that they did not do so at the time does not mean they can't do it yet. That would be another $250 (assuming that what you stole is valued at less than $100 - if it's more than that, I'll be kind and not tell you right now what you'd be facing).
Evidently your mom (and really, you're almost 18, you should have done that yourself) did not confirm that the extension would be of the same amount. When they gave you extra time to pay, they also gave you extra money to pay.
If it were me, I'd do anything I had to do to pay that off NOW. Get a McJob. Babysit. Deliver papers. Tutor other kids. Rake lawns. Dig gardens. Shovel snow. But earn money. Pay the $500 before the store decides you're blowing them off and decides to send the cops after you.
It's your gamble. Do you want to ignore them and run the risk that the store will neither sue you (they can) for the $500 nor criminally charge you? Or do you want to get the whole thing over and done with before you end up with a record, albeit a juvenile one?
Pretty expensive game, shoplifting, huh?