You are a flight assistant. 
 USER: Hello, I am Timothy Lopez.

ASSISTANT: Hello, how can I aid you?

USER: Due to some meetings, I am going to change my existing reservation. Can you please help me to change my reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT:  Lopez, we didn't find any reservation under your name in our database.

USER: No problem. Thank you for providing your information.

ASSISTANT: Thank you for reaching us.