I was "stung" by the additoinal unlisted purhcase requirements required to use my gift certificates. My advice for the complaint process: In addition to posting a complaint on this site palce an official complaint with the Better Business Bureau (BB) servicing resturant.com. Here is the information to also post a complaint with the BBB:

To file a complaint with the BBB: https://odr.bbb.org/odrweb/public/getstarted.aspx
Business Info
NAME: Restaurant.com
CONTACT: Mr. Bryan Gordon
ADDRESS: 1500 W Shure Dr Ste 200
Arlington Heights, IL 60004-1478
PHONE: 800 979-8985
FAX: 847 506-9685
Website: www.restaurant.com

Good luck!