You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER:  I want to change in my dates of reservation, as some more friends are need to join us if I am changing the dates, can you please help me?

ASSISTANT: Sure. Please tell me your name?

USER: My name is Helen Williams.

ASSISTANT: Please wait.

USER: Ok.

ASSISTANT: Sorry, no reservation found under your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for reaching us.