You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I abet you?

USER: I am Timothy Carter. I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, let me check the data base and revert you.

USER: Sure.

ASSISTANT: We found a reservation on your name. Can you provide your updated details?

USER: I would like to travel on 07/16 to 07/18. My source point is LAS to OAK.

ASSISTANT: Thanks for giving your details. There are no fights available eon your required dates at this moment.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for opting us.