You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: Sharon Brown here. I have some unplanned work in my office, so I will not be able to travel to Houston on my scheduled dates. So I want to reschedule my itinerary dates. Could you help me out?

ASSISTANT: Sure, I am here to help you with this.

USER: Ok.

ASSISTANT: Sorry Brown, there is no reservation found under your name to reschedule any reservation.

USER: No problem, thank you for your assistance.

ASSISTANT: You are welcome always.