I would call and negotiate a payment plan. It can affect your credit if they decide to take your to civil court. I don't know the deal that this retailer has with this law firm, but some retailers have it written in their contract for the firm to take the subject to civil court. Remember, the law firm only makes money if they collect, so I would suspect they will take you to court.
My advice is for any debt owed. Talk to them and negotiate a deal in writing.

