Don't know what the policy is at your company, but at mine you have to use to Company website (and generally book UA, US or DL domestically)...except if you can get a cheaper fare elsewhere. Thus they do allow for web fares, special promotions, sales etc. They also allow us to fly F when travel entails a flight of 4+ hours, and CO's been having Z domestic sale fares that come in cheaper than 'fully refundable Y', so I'm able to book on CO. Also if I have a credit, voucher etc--the travel agency can't use them, I have to book directly with CO to receive the credit.