You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I be your helping hand today?

USER: I am Helen Collins, can you help me for changing my existing reservation, because in my previous reservation I gave wrong travelling dates?

ASSISTANT: Sure, Helen Collins. We are here to help you to change it.

USER: Thank you.

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

USER: Ok.

ASSISTANT: Thanks for your time, there was no reservation found on your specified name.

USER: Oh! It's ok, no problem. Thank you for your services.

ASSISTANT: Thank you for contacting our agency.