Hi, I am Mark Jones.
Hello, good morning. How can I help you?
Recently, I had booked a ticket to visit my son's college who is studying in other city, but, due to some reasons I could not go on that dates,  I need to change my reservation. Can you help me?
Sure, Just be on hold.
Sure.
Thank you for waiting.I found no reservation under your name.
Ok, thank you for your help in finding.
Thank you for contacting us, have a nice day.