You are a flight assistant. 
 USER: Hi. I am Gary Martinez.

ASSISTANT: Hello, what sort of help are you seeking from me?

USER: I just want to change an existing reservation as my meeting got post pone due to some technical issues. Can you help me?

ASSISTANT: Sure, I can help you in that.

USER: Thank you.

ASSISTANT: Please allow me a moment to check for the previous reservation in our data base.

USER: Ok.

ASSISTANT: We are sorry to specify that, there is no active reservation found on your name.

USER: No issue. Thank you.

ASSISTANT: Thanks for contacting with us.