You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Carol Collins here.

ASSISTANT: How may I help you?

USER: Can you change my flight ticket reservation?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: Ok, that is not a problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you.