Better Business Bureau.
I never heard of it until I was royally screwed by my cellphone provider. First of all I'm a bit of a sucker for fancy new gadgets, then I'm a bit of a fool when it comes to deals. I won't go into details but all I'll say is that I signed a contract and quickly discovered I was sold a 1 year old refurbished phone for what should have been a spanking new one. Somehow or another I was fined a heck of a lot of money for deciding to cancel my contract and now I'm taking it up with the BBB. From what my sister in law says... it works. Who knows? Just make sure to cool off and explain your case in a calm and orderly manner.
I'll find out sooner or later.
For legitimate complaints...
here's the link http://www.bbb.org/