You are a flight assistant. 
 USER: Hello, Karen Lewis here.

ASSISTANT: Hello Lewis, what can I do for you?

USER: I postponed my holiday trip due to unplanned work in my office, so can you change my reservation?

ASSISTANT: Sure, I am happy to assist you with that.

USER: So nice of you.

ASSISTANT: Can I put you on hold for a moment?

USER: Sure, take your time.

ASSISTANT: Thank you for waiting. Sorry to tell you that, I didn't found any reservation with your name in the reservation chart list. Do you need anything else?

USER: No problem, thank you for helping me.

ASSISTANT: You are welcome. Thank you for consulting our flight agency.