You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Elizabeth White.

ASSISTANT: Nice to meet you Elizabeth.

USER: I want to do some changes in the existing reservation because my friends are not able to come on those dates, can you please help me in changing my existing reservation?

ASSISTANT: Sure, give me a minute.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found. Thank you for contacting us.

USER: It's ok, thank you for your help.

ASSISTANT: Welcome.