Don't count on them caring, unless, you have evidence it is a ring with extensive activity. Occasional screwing of citizens isn't a big deal to them.
Same with the USPS inspectors of fraud and other mail crime. Just them mailing false documents is a crime, but again, if it isn't big enough to be worth their time, they don't do anything.
This is the contact info for Michigan as copied from the FBI website.
https://www.fbi.gov/contact-us/field-offices/detroit
Direct phone # (313) 965-2323