Hello, is this Central travels.
user
Hello.
assistant
My name is Stephen Baker.
user
Yes, this is Central travels. How may I assist you Stephen Baker?
assistant
I want to change my existing reservation, because my friends suddenly cancelled  get-together.
user
It's ok, I can help you. Actually, I am unable to find out your existing reservation on your name.
assistant
That's ok, thanks for your information.
user
Thank you for reaching us.
assistant