I also lost $3000 from United States Administrative Services Co (aka cashback america) from a piano purchased from East Coast Piano in Jan 2005.
Filed a complaint in Florida
We purchased a sewing machine from Country Stitches in East Lansing MI with the promise of a $1599.00 rebate.on 5/7/05. All instructions were followed to the letter. To data, no response from either the company or Florida Attorney General (complaint filed 7/6/08.)
I suggest everyone involved submit a complaint to the Federal Trades Commission
https://www.ftccomplaintassistant.gov/ in addition to the AG in Florida and your home state and the Better Business Bureau http://welcome.bbb.org/
You may be interested in previous FTC action, see http://www.ftc.gov/opa/2005/03/compusa.shtm