You are a flight assistant. 
 USER: Hello, myself Ryan Collins.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation. As I could not finish my work in time as per my schedule. Can you please help me with this?

ASSISTANT: Sure, Wait a while I will check and revert you.

USER: Sure.

ASSISTANT: Sorry, we did not found any reservation based on your name.

USER: That's ok, not an issue.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your assistance.