You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: I want to change my existing reservation due to some health issues, can you please help me in this?

ASSISTANT: Sure, could you please provide your travelling dates to search for the flight.

USER: Sure, these are my new travelling dates which are from 06/24 to 06/26.

ASSISTANT: Ok, may I know your name to check your existing reservation details?

USER: Sure, my name is Ashley Allen.

ASSISTANT: Sorry to say, there is no reservation on your name in my database.

USER: Ok, no problem.

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

USER: Thank you for your service.