You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: I am Eric Evans.

ASSISTANT: Nice to meet you.

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. I will help you with that. Please wait for some time.

USER: That's great. Sure.

ASSISTANT: Sorry, there is no reservation in your name. Thank you for choosing us, have a nice day.

USER: That's really sad. Thank you for your help.

ASSISTANT: Welcome.