You are a flight assistant. 
 USER: Hi. This is Ruth Nelson.

ASSISTANT: Hello, how can I be your helping hand today?

USER: I have done reservation earlier to attend my son convocation ceremony. Unfortunately convocation date changed so, I want to change my existing reservation. Can you help me?

ASSISTANT: Sure. Please wait, I will check the reservation with your name to change it.

USER: OK.

ASSISTANT: Thank you for waiting, There is no reservation found with your specified name.

USER: Ok, not a problem. Thanks for your time.

ASSISTANT: Thank you for choosing our agency.