You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, may I know your name for the change process?

USER: My name is Steven Hernandez.

ASSISTANT: Your reservation found. Can you confirm your planned travel dates?

USER: My travelling dates are Mar 18 to Mar 20.

ASSISTANT: May I know your planned airport codes?

USER: My new airport codes are CLT to DCA.

ASSISTANT: Do you have any limits on number of connections?

USER: I need a flight with single connection.

ASSISTANT: Any another specifications on your journey?

USER: No.

ASSISTANT: Unfortunately, no flights available on your requirements.

USER: No problem, thanks for your information.

ASSISTANT: Welcome, thank you for reaching us.