Say they are USDA Vendor Compliance Office. Send a sample USDA letter asking for business trial balance or statement of account. This is for vendors doing recovery work for different agencies of the government. Still sounds fishy.
The address in the letter matches with a UPS store in a strip shopping center. Sounds even fishier with the Federal Gov using a UPS store to do business out of.
The same people called me yesterday using the same number. While I was asking questions it sounded like a call center in the background with lots of other people talking. I am not inclined to provide any information. Plan to send faxed documents to the agencies we have done work for to verify.