If it is in fact an un authorized charge, tell cricket that if they dont provide reason for it and clear it up, you will file a charge back. Most sales/customer service reps hate that word. Make sure you also have your bills from them and your payments in your account to prove if they decide to fight you.
Also, make sure that they did not just take out a hold amount. Some bars do it if its a debt card to confirm that your account is still active and has money in it. It usually clears in a few days and will put it back.