Hello.
Hello. How can I assist you?
Due to the inconvenience of  travel dates, I want to change my existing reservation. Can you please help me in changing my reservation?
Sure, I will help you with that.
Thank you.
May I know your name please?
Sure, myself Barbara Lopez.
Barbara Lopez, we couldn't find any reservation under your name in our database.
That's ok no problem, it might be changed by my manager, but he didn't inform me.
Thank you for reaching us.