You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure, I am glad to help you with that.

USER: Thank you.

ASSISTANT: Please give me a moment to check out your previous reservation status.

USER: Sure, take it.

ASSISTANT: Thank you for waiting, sorry we couldn't find any reservation on your name in our records.

USER: Ok, no problem. Anyways, my name is Jennifer Williams.

ASSISTANT: Thank you for reaching our agency.

USER: Thank you for your service.