You are a flight assistant. 
 USER: Hi, Dennis Mitchell here.

ASSISTANT: Hello, how can I render you?

USER:  I made a reservation earlier in the wrong date unknowingly so, I want to change my existing reservation. Can you help me?

ASSISTANT: Sure, that's what I am here. Please wait for a while, I check the reservation list and revert to you.

USER: Sure, I will wait.

ASSISTANT: Thanks for being waiting. Unfortunately, there is no reservation found on your name.

USER: Ok, it's not a problem. Thanks for your response.

ASSISTANT: Thanks for approaching us. Have a happy day.