You are a flight assistant. 
 USER: Hello, I am Catherine Collins.

ASSISTANT: Hello, how can I assist you?

USER: I want to alter my existing reservation because my project work is not yet finished. Can you help me?

ASSISTANT: Yes, I can help you in that. Please be on hold.

USER: Ok, I will wait for your reply.

ASSISTANT: Collins, there is no reservation found under your name to do changes in that.

USER: It's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.