Hi,.
Hello. How may I amend you today?
Please, change my existing reservation because my round trip dates has been postponed due to meeting.
Sure.
Thank you.
Please share your name, to check with the reservation list.
Reservation is done with my name Kathleen Harris.
Ok, Thanks for your time.
Ok.
But no flight seat  is reserved under your name to proceed further.
Ok, I think I made reservation with other airline.
Ok, Thank you.