You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am David Davis, I need to change my earlier reservation as my plan to visit my friend's home got postponed. Will you help me with that?

ASSISTANT: Sure, please be on hold.

USER: Sure.

ASSISTANT: Thank you for your time. Sorry, we did not find reservation in your name.

USER: It's ok. Thank you.

ASSISTANT: Thank you for opting us.