You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I oblige you today?

USER: Please help me to change an existing reservation due to my health issues.

ASSISTANT: Sure, we are here to make your work ease. May I know your name to check your details in our database?

USER: I am Gregory Lopez.

ASSISTANT: Please wait for a minute.

USER: Ok.

ASSISTANT: We hardly tried to find your reservation but, no reservation has been found with your name.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for choosing us.