Hi.
Hello.
I am Lisa Gonzalez.
How can I help you Lisa?
Can you help me for changing my existing reservation?
Sure, please wait for a moment.
Ok, I will wait for your reply.
 I have checked and seen that there is no reservation found under your name.
Oh! It's ok, I think my sister already changed my reservation. Thank you for your quick response.
Thank you for approaching us.