You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I be there for you.

USER: I am Mary Edwards. I want to book a flight ticket to Oakland, OAK. Can you help me in booking on 09/18?

ASSISTANT: Sure, may I know when would you like to return on?

USER: I will be return on 09/20.

ASSISTANT: Could you please mention your source details?

USER: I am boarding at Houston, HOU.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Thanks for waiting, there are no flights available at this moment on your required dates.

USER: Ok, No issues. Thank you.

ASSISTANT: Thank you for reaching us.