You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: Actually, I planned the trip but it take too long time to reach, so I just planned for some other locations. I need to change my ticket. Can you help me in that?

ASSISTANT: Yes, I can help you with that.

USER: Thank you.

ASSISTANT: Can I know on which name the reservation is booked?

USER: Yes, it is booked under the name Dennis Lewis.

ASSISTANT: Ok, I have found reservation on your name.

USER: That's great.

ASSISTANT: Can I know your new travelling airport codes?

USER: Yes, the new travelling airport codes are IAH and ORD.

ASSISTANT: Ok, could you tell me your dates of travelling?

USER: I preferred to travel in these dates 02/09 and 02/11.

ASSISTANT: Ok, give me a second. I will get back to you.

USER: Ok, take your own time.

ASSISTANT: Sorry to inform you that there is no flight found on your requested dates.

USER: It's ok, anyway's thank you for searching.

ASSISTANT: Thank you for reaching us.

USER: Welcome.