You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I guide you for the day?

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

ASSISTANT: Sure, I am here to help you out in changing your reservation.

USER: Than you, I will wait for your reply.

ASSISTANT: Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our reservation list to change it.

USER: That's fine, thank you for your service.

ASSISTANT: You are welcome, thank you for reaching our agency.