Well...the landlord is wrong in his response to you. Florida law requires a landlord to send you a notice in writing of their intent to place a claim against your security deposit. If you left a forwarding address, the landlord has to mail you the notice within 30 days of the date you vacated. Failure to do this bars the landlord from deducting any portion of your security deposit. This does not mean that the landlord can't come after it later in a small claims action against you.
Once you receive the notice, you are required to respond in writing within 15 days back to the landlord that you dispute the amounts being deducted. If you fail to do this, they get to keep the deposit (or at least a portion of it if the damages incurred are less than the deposit). If you dispute the claim made by the landlord within the time frame provided, you either work it out, or one of you files a small claim suit to determine who is entitled to the deposit funds. At that time, the landlord would need to prove his/her damages being assessed.
Hope that helps.
Yes you can dispute the claim to your deposit. The landlord was supposed to send you a notice claiming the deposit. You should see a tenants rights attorney to find out if you have a claim for the recovery of your deposit. The landlord may have to pay the deposit and your attorney's fees. There are attorneys that will take these cases on a contingency basi, which means that you do not have to come up with money to hire the attorney.