Hello, Donald Thompson here.
Hello, how can I give assistance to you?
Due to my earlier reservation unknowingly  the wrong dates can be mentioned so, I want to change my recent reservation. Ok, don't change it, please cancel my reservation. Can you please help me with cancellation?
Ok, I will help you. Please wait a minute.
Sure.
Your ticket has been cancelled.
Thank you.
We will refund your money soon to your wallet. Thank you.