You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. In which way I can assist you right now?

USER: My name is Katherine Robinson.

ASSISTANT: Glad to meet you Robinson.

USER: I just need your help in changing my existing reservation details.

ASSISTANT: That's fine, I am happy to help you with changing an existing reservation. Please be hold on for a moment, I will check whether reservation existing or not to change.

USER: Ok.

ASSISTANT: I should appreciate your patience. Sorry Robinson, I did not came across your name in the reservation list to change your reservation.

USER: No problem, thank you for the information.

ASSISTANT: Most welcome. Thank you for choosing us.