SAR Associates This company sent a letter threatening to take legal action against me for non payment for a loan that they won't identify. Plantation Florida

SAR Associates sent me a letter advising me that I have an account that is severely past due and is now active in their internal Civil Procedures Departmeent. It claims several attempts to resolve the matter with me and I have ignored them. 

They claim I did not pay a loan for $1450 to LTS Management in June of 2012. When I contacted them about the matter they refused to provide me with any information as to who this company that I allegedly owe the money to is. 

I researched the company which is out of business and there is no contact numbers that are working. Also, I contacted my bank, had it researched and there was no such deposit made into my account.

I contacted SAR Associates several times about this matter with no success. I even Faxed bank statements from that time period to provide them with proof that no monies by this company were ever deposited.

They want me to make some type of payment. I refused to do that. They informed me that I have the burden of proof to provide information that I never made this loan. I informed them that they need to provide proof that I made this loan. They then informed me that I will be brought to court. Is this a scam?