You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I am David Martin. I need to modify my dates in my reservation, can you help me out please?

ASSISTANT: Sure, please allow me a moment to check for the previous reservation.

USER: Sure, take your own time.

ASSISTANT: David, there is no reservation found under your name.

USER: That's ok, no problem. Thank you for your information.

ASSISTANT: Thank you for reaching us.