You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Thomas Adams. I would like to change my existing reservation, can you please help me?

ASSISTANT: Sure, please wait for a moment.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry, there is no reservation found on your name in our database to change.

USER: No problem, thank you for checking.

ASSISTANT: Thank you for reaching us.