There is a possibility that this is a scam. It sounds like a new twist of a very common scam going around where people are getting called about payday loans they never took out.
I have not heard of a company collecting back taxes on cars. States do use Collection Agencies to collect back taxes, but cars are usually handled through the DMV(or what ever the agency is called). If you don't register a car on time nothing happens at that time. But if you do get stopped you get fined. Only when you go back to the DMV to get current on your registration is when they "hit" you for anything past due. You can not get a current registration until you pay the past due amounts.
They seem like they are using outdated information that could even easily be found through public records, or through applications you may have filled out at various times. You also can not reach them, this either means they are never open or they are using "throw away" cell phones and that number was disconnected. These aregood indications of a scam.
Other indications that it may be a scam.
Did these people have a foreign accent?
Were they very agressive, even going as far as saying you will be arrested or there is someone on the way to your house to serve you with papers?
Do they want immediate payment through a Moneygram or want you to go buy a Walmart Debit Card and give them the numbers?
Have they only called you by phone, never sending you a letter?
Have they called people you know threatning them as well?
If any of those is true there is a good possibility that you are being scammed.
Now, if this is a "real" debt, you need to send the company a Debt Validation letter. There are many templates you can find on the Internet. The important thing is that you must send it Certified Mail with Return Receipt, and DO NOT sign it. If they can not validate the debt the can not collect on it.
What ever you do DO NOT send them any personal financial information. If you don't have an issue with Identity Theft now, sending even a "legitimate" collection agency information such as Tax Records is going to open yourself up to many more issues.
