You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am James Clark. I have to stay with my mother as she is unwell, can you please help me to change my flight reservation?

ASSISTANT: Sure, please wait a moment.

USER: Sure, I will wait for your reply.

ASSISTANT: We found a reservation with your name. Kindly share your travel dates.

USER: I want to depart on Nov 15th and I will return back on Nov 17th.

ASSISTANT: Could you please provide me your airport codes?

USER: I want to travel from PHL to DFW.

ASSISTANT: Sorry to say, no flights found with your requirement.

USER: No problem. Anyway, thank you for checking.

ASSISTANT: Thanks for reaching us.