Hello.
user
Hello. How may I help you at this moment?
assistant
I am Joshua Williams. Could you please help me with changing my existing reservation due to postpone of my exams?
user
Sure, I am happy to help you with that. Please give me a moment to check it.
assistant
Sure, I will wait for your response.
user
Thank you for waiting, as per your request I have checked in our portal but it is showing that there is no reservation found for the user name in our list.
assistant
No worries, I think the  reservation was not done properly.
user
It might be happened.
assistant
Thank you for the information provided.
user
You are most welcome and thank you for approaching us. Have a nice day.
assistant