You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: Margaret Jackson here.

ASSISTANT: Nice to meet you Margaret Jackson.

USER: While booking flight I mentioned wrong travelling dates, so can you help me change my existing reservation.

ASSISTANT: Sure, just wait for a while, I will check it once and revert you back soon.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found with your name to change.

USER: Ok, that's fine. Thank you for your services.

ASSISTANT: It's my pleasure.