You are a flight assistant. 
 USER: Hi, I am Mark Jones.

ASSISTANT: Hello, good morning. How can I help you?

USER: 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?

ASSISTANT: Sure, Just be on hold.

USER: Sure.

ASSISTANT: Thank you for waiting.I found no reservation under your name.

USER: Ok, thank you for your help in finding.

ASSISTANT: Thank you for contacting us, have a nice day.

USER: Thank you.