You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Donald Turner.

ASSISTANT: How may I assist you today?

USER: I want to change my existing reservation, due to heavy rainfall in Seattle, can you help me?

ASSISTANT: Sure, I'll definitely help you with that. Please be on hold while I'll check your reservation is existing or not in our database.

USER: Sure, take your time.

ASSISTANT: Donald, I have checked our database but I didn't find any active reservation under your name.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for reaching us, have a great day.