Hi.
Hello, how may I help you today?
Could you help me to amend my existing reservation?
Sure, I can change your reservation right now. Before that I need to know your good name please?
I am John Williams.
 Thank you. Please stay online for a while, I will check your reservation status and let you know.
Sure.
Sorry to say that, there is no active reservation found on your name.
Not  a problem, thank you for the information.
Thank you for availing us.