Hello.
Hello, may I know how best I can help you today?
I am Charles Phillips. I want to change my existing reservation. Could you help me with that?
Please wait for a while.
Ok.
Your reservation found, can you please share your details.
My travelling dates are from Dec 12-14.
Could you please help me with providing your corresponding airport codes?
My airport codes are IAH to LAS.
 No flights are available on respective dates of travel.
That's ok, no problem. Thank you.
Thank you.