How to determine if law office is official

You are right to be skeptical, as there are so many scams out there.  From what you say, they have not provided you any proof of their legitimacy and until they do so, I would not send them any money.  Did they have information about the debt you owe that would suggest they got the information from the source?  A law firm without a website?  I have never heard of such a thing.  If they file a lawsuit against you, then you will know it is legitimate and you can deal with it at that point, but until then I would be tempted to tell them "so sue me" or to demand they stop calling.   This answer is given in accordance with the laws of Virginia and may not be applicable in any other state.  It should not be construed as legal advice, as that would require a more thorough analysis of all of the facts involved in a specific case.  If you need further information or assistance, please feel free to contact my office for a consultation. Case results depend upon a variety of factors unique to each case. Case results do not guarantee or predict a similar result in any future case.