Globaliser

If you write down what the agent says, it would be some evidence that the agent looked at one thing on his screen and said something different. That's a high hurdle to surmount, given that the agent would have had to have seen one flight number on his screen and told you a different flight number, and then seen one departure time on his screen and told you a different time - and then the wrong flight number and the wrong departure time happen to match. But it's not impossible that that's what he did, and some written evidence from you would be better than none if you need to try to show that he got it wrong.