Is this going to far? And what can I do?

Right now I have a balance from a credit card company that has now been referred to a collection agency for payment. The collection agency has called me stating that they were a law firm and if I didn't make a payment right away then they would seek a judgement against me. These calls go on all day, every day. They call my job and hit "0" for the operator and harrass the secretary saying that they are a law firm (which they are not) and that they are going to cease my property and garnish my wages to collect the debt. The balance is 1,400 and one women went so far as when I told her I could not make a payment on it until next week, told me that my credit card number was still on file and charged my card for $400 and advised me very nasty that she was going to take it whether I gave her permission or not because I owed her the money, and it was her's for the taking. Since it was a check card she charged I called my bank as soon as I saw the charge on-line later that day.They did reverse the charge but Is there any legal action I can take against them. What this company is doing is going to far. Please help!