Was this a divorce case? Did you sign a retainer agreement? Was all of your retainer fee used up when you fired the lawyer, or did you have an outstanding balance? Write back once you clear these up, and I'm sure your question will be answered to your satisfaction.
Request an accounting from the firm to see if you have any retainer left. Try to work it out with them, if that doesn't work you can sue in small claims or get an attorney to write a demand letter. Sometimes there are few remedies when the amount at issue is small (in legal terms).
Though we strive to provide accurate legal information in our answers on AVVO, our answer should not be construed as legal advice and it does not create an attorney-client relationship. Our firm only forms attorney-client relationships by written agreement signed by both our firm and the client. Please seek an in-person consultation with an attorney immediately as almost all legal matters are time sensitive and failing to meet deadlines can result in adverse consequences.
Keep in mind the lawyer gets paid for the time he or she puts in. You can request the time records and see what work was done. A reputable lawyer will account for the time and refund the portion of the retainer that is not earned. If they sent you a bill for $600, you really need to get this worked out so they do not try to collect from you in the future.