You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER:  I want to do some changes in my existing reservation because I did not get the concert tickets, so planning to travel on another date, can you please help me?

ASSISTANT: Sure, can you please provide your name?

USER: My name is Nicole Martin.

ASSISTANT: I am sorry, there are no previous reservation with your details.

USER: Ok, no problem, thank you for your help in searching.

ASSISTANT: Thank you for approaching us.

USER: Thank you.