Georgia law has pretty strict rules for landlords holding security deposits, and in my experience (both as a lawyer and as a renter back in law school) those rules frequently are not followed. The rules include documentation requirements of the reason the deposit is being withheld. If the landlord fails to follow the rules set forth by law, then he or she is potentially subject to penalties of treble damages (meaning 3 times the amount of the deposit you are owed).
I would recommend reading the law and giving a copy to your landlord. The statutes can be found in the Official Code of Georgia, Sections 44-7-30 through 37. If that doesn't solve the problem, you can always take the case to court, but you might benefit from having a lawyer at that point.