You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: I am Thomas Perez, planning to change my existing reservation. can you help in that?

ASSISTANT: Sure, I am here to help you.

USER: Ok.

ASSISTANT: Please wait for a couple of minutes, I will check the reservation on your name to change it.

USER: Ok.

ASSISTANT: Thank you for your patience, we are sorry to say that there is no reservation found on your name.

USER: Thank you for your response.

ASSISTANT: Thank you for approaching us.