You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: I would like to change my flight reservation due to some personal issues, can you please help me?

ASSISTANT: Sure, let me know your name to check your reservation details in our database.

USER: Sure, I am Sarah Taylor.

ASSISTANT: I am sorry to say you that there is no reservation found under your name in our database.

USER: Sad to hear that, thank you for checking.

ASSISTANT: Thank you for reaching us.