Debt Collection Service

I am being constantly harrassed by a debt collection agency, Folk Receivable Management. I don't know where they are located. The telephone number is 678-228-3415. I have tried to call them on numerous occasions to tell them that they are calling the wrong person. They are rude and disrespectful and hang up in my face. I am considering taking legal action and need to know if you can help me find out where they are located.