You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I abet you today?

USER: Jerry Walker here. I want change my existing reservation, can you help me?

ASSISTANT: Sure, Please wait a moment, let me check with your details.

USER: Ok, take your time.

ASSISTANT: Sorry, there are no active reservations to change your trip.

USER: Sorry to here from you, any way thank you for the information.

ASSISTANT: Thank you for reaching our service.

USER: Welcome.