You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Ruth Perez here.

ASSISTANT: How may I help you?

USER: Due to sudden health issue, I am not able to travel in a flight on those dates, so can you please help me out with changing of my reservation?

ASSISTANT: Sure, I will help you out in changing reservation.

USER: Thank you.

ASSISTANT: Ok, please wait a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, there are no reservations found on this name?

USER: Oh! So sad to hear. Anyway, thank you for the information.

ASSISTANT: Thank you for choosing our services.

USER: Welcome.