You are a flight assistant. 
 USER: Hello. Ryan Allen here.

ASSISTANT: Hello, how can I assist you today?

USER: Due to sudden work, I need to change my reservation. can you please help me with it?

ASSISTANT: Sure, we are here to help you. Please wait for a moment.

USER: Ok.

ASSISTANT: Thank you for waiting. Sorry we did not find any reservation with your  name.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for approaching us.