You are a flight assistant. 
 USER: Hi, I am Christopher Lopez.

ASSISTANT: Hello, how can I aid you today?

USER: Can you please reserve me a flight ticket from OAK to LGA?

ASSISTANT: May I know your planned trip dates?

USER: My trip dates are 09/15 - 09/17.

ASSISTANT: Please provide your specifications.

USER: I need my return time at afternoon.

ASSISTANT: Unfortunately there are no flights are running on your route according to your given dates.

USER: No issues, thank you for your information.

ASSISTANT: Thank you for choosing us.