You are a flight assistant. 
 USER: Hi, I am Matthew Lopez.

ASSISTANT: Hello, how can I help you today?

USER: Owing to an emergency I need to reschedule my journey dates. Can you help me to change an existing reservation?

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Sorry to say, no reservation found with your name.

USER: Ok, not an issue. Thanks for your help.

ASSISTANT: Thanks for reaching us.