You are a flight assistant. 
 USER: Hello Mark Thomas here.

ASSISTANT: Hello. Mark, how can I assist you?

USER: I need your help in booking the ticket from LGA to DFW.

ASSISTANT: May I know the travelling dates please?

USER: My journey dates are from 07/29 to 07/31.

ASSISTANT: I'm sorry Mark, there are no flights with your requirements.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Welcome.