You can send them a demand letter, or better yet, hire a lawyer to send them a demand letter, but if that doesn't work then your only option is to file a lawsuit.
In Florida the small claims court limits is $5000. If your case is under that then you can represent yourself and file in small claims court.
The process of a lawsuit is essentially the same everywhere, with a few, minor procedural differences.
A lawsuit generally follows this process:
1) File the petition in the court with jurisdiction and venue. The court with jurisdiction and venue is usually where the defendant resides or has their place of business. You also have to look at the amount you intend to sue for to determine what court is correct
2) When you file the petition with the clerk of courts you will pay the filing fee and also ask for citation to be issued and service to be done. The clerk doesn't serve the papers so ask them if you have to take them to the sheriff's office for service or if they will do it. Just follow their directions as to that.
3) The sheriff will serve the defendant with the lawsuit.
4) The defendant will file their answer.
5) You can then do some discovery if necessary but you will need to check with the clerk and ask if your court allows discovery. Some small claims courts do not.
6) After that the next step is to set the case for trial.
7) During the trial you introduce your evidence and they introduce theirs.
8) The judge renders a judgment and a written order is entered.
That is the basic process of a lawsuit.
If you are going to represent yourself, you need to educate yourself on how to handle a lawsuit. There are a number of good and inexpensive ebooks at the link below. TO start the process I'd advise you to look at the one on small claims cases and on legal research. Later you may want to add some of the others:
If your question has been answered then I'd offer my best wishes to you and ask that you please not forget to leave a Positive Rating so I receive credit for my work. Of course, please feel free to ask any follow up questions in this thread. I want to be sure that all of your questions are answered.