check cash usa inc

Nhi, Inc posted a $ 6.23 check in the mail, why?
My GF received a check for $ 6.23 valid for Nhi, www.nighthawkinvestigations.com Inc by Guarantee Federal Bank Mesquite, TX. Www.bank.guarantygroup.com I called the Chamber of Commerce that have Mesquitte many calls from across the U.S. about these controls, but did not know anything about Nhi, Inc. went to Dallas and discovered nhi BBB = Nighthawk Investigations, Inc. call (972) HAWK-222 and verified the authenticity of the control, but did not give me any information on why it was – I just lost the billing department for a few minutes! Has anyone collected the checks? If so, what happens? Why do they want you to put your account number on the back? The Chamber of Commerce Mesquite informed me that a few people were in contact with your tax status, but the girl was not specific as to "why." Thanks advance for your answers.
Is there any small print on the check indicating an agreement to anything? that the company has nothing to do with your insurance company? could be a rembursement of an overpayment. if you can not do and I need the money, only to destroy it and walk away. SNS Inc. name sounds fishy.
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