They SHOULD have sent the notices by certified mail, return receipt requested. At the least, I think they are required to get a proof of mailing certificate stamped at the post office when they mail the letter. But I know from dealing with a company here in VA, they don't even follow that requirement.
From my understanding of reading FL law, if the judge didn't sign the garnishment than it isn't legal. Again, call the clerk of court for your city and ask for the status on your filing.
have you kept all of the letters and the envelopes they came in, so you have proof of postmarking for the letters you received?
He's not licensed in FL, but you might send a personal message to VA-Legal-Defense to ask him to read over the law and give his professional opinion on it. Wouldn't hurt.
In the meantime, I would talk to your employer and let them know that the garnishment may not be valid so THEY need to check into the legal validity of it as well. I don't know what the ramifications are if the CA and your employer unlawfully withheld a garnishment from your pay. There may be a consumer group in your area that could provide more FL-related advice. I would also contact your state office of consumer relations/ consumer protection (whichever they are called in FL) AND the FTC because all collection agencies operating in the US must be registered with the FTC. File complaints.