I am not sure what you mean when you say the criminal charge part is squared away - apparantly it means you have no further questions about it. The reason I raise that part is the only real value of paying the civil demand is if it can lead to a dismissal or more favorable sentencing in the criminal case. Most of the posts on this site recommend not paying the civil demand because it is unlikely that the store would spend the time and money to sue you. Here, you have paid the face value, and now are being asked for additional fees. If you do not pay the consensus is that not much will happen. If you are very upset about Palmer you might repost a question in the consumer law section of AVVO and see if you have any responses regarding deceptive debt collection practices. good luck.
PAY NO MORE. You have already overpaid to the tune of $430.00. Do not throw good money after bad. Do not communicate any further in any fashion with the law firm.
Don't pay these attorneys. You've already paid enough criminally and civilly. Nobody will sue you for the pennies they claim you owe them.