so the GA said one thing by mistake and the computer overrode her, printing the correct $300. A seasoned WN traveller knows to ask what time the new flight gets in rather than how much $$.

I had the opposite occur--a gate agent/supervisor offered $400 for the value of a companion pass holder's 'free' ticket. ($200 "value" plus $300 compensation). Computer printed it at $400 and wouldn't let them override. End result: they kept their original promise by printing a discretionary comp, a second $100 luv voucher.