warrant of debt & statute of limitations

I need to know what to do about a doctors office threatening to file a warrant in debt against me. I never saw anyone at this office. I believe an acquaintance used my ID to be seen at this office (she also stole a credit card). I spoke to an employee at the office in 2006 and thought the matter was resolved after I explained that I was not the patient even though my name and personal information was in their computer. She assured me she would "take care of it". I assumed she did, because I did not hear from them anymore....until today. I tried to explain the situation to the person who called today, but she would not listen and kept interrupting me. She states they have a copy of my drivers license, so she knows I was the patient. The person who stole my drivers license and credit card has the same color hair, so I guess it is perceivable that this other person could have actually been seen if the office staff did not actually look closely at the license. At any rate, the "debt collector" who called today was rude and insisted that I was responsible for the bill because she was able to find out where I lived and my phone number, therefore she was going to file the warrant in debt against me. She did shut up long enough for me to ask how old this debt was. She stated it was from 2005. The statute of limitations in VA is 3 years. I know legally, they are not able to collect this debt because of the statute of limitations. I tried to explain this to the debt collector, but she just started on another rant about how I should get a lawyer, because they were going to get the money anyway. Not only should they not be trying to collect this money from me- it is too late to even go after the person who really saw the doctor.
What do I need to send to this doctors office to prevent the warrant in debt from being filed. I know they can't collect on this debt, but I don't want the headache of dealing with it. I also want to make sure the record is cleared so this somehow does not end up on my credit. Is a letter to the office sufficient (if so what should I say) or do I need a lawyer to file a cease and desist. Do I need a lawyer when this is not my debt to begin with.