You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I hand help full to you?

USER: I am Margaret Jackson.

ASSISTANT: Nice to meet you Jackson.

USER: Due to my health problem I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Sure, I am happy to help you. Please wait for a moment to check your previous booking.

USER: Sure, take your own time.

ASSISTANT: I am sorry Jackson, I am unable to find your previous booking to modify it.

USER: That's fine. Thank you for your help.

ASSISTANT: Your ticket is not booked properly I think. Anyway, thank you for your valuable time.