You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: I want to change my reservation which is done recently due to some problems, can you please help me?

ASSISTANT: Ok, I will assist you with that. Please wait a moment. Please can you mention the name for which the ticket is been booked?

USER: Sure, I will wait. Sure, my name is Dorothy Green.

ASSISTANT: Ok, thank you for waiting.

USER: My pleasure.

ASSISTANT: Sorry, there is no reservation found on your name to change.

USER: Ok, not an issue. Thank you for your service.

ASSISTANT: Thank you for choosing our agency.