You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Due to sudden work, I want to change my reservation. Can you please help me with it?

ASSISTANT: Sure, please mention your name to check your reservation details in our database.

USER: Joseph Garcia here.

ASSISTANT: Thank you. Please wait for a while, let me check your reservation status.

USER: Sure, I will wait for your response.

ASSISTANT: I'm happy to inform you that I have found a active reservation on your name. May I know your preferable travel dates?

USER: My travelling dates will be on July 6 to July 8.

ASSISTANT: Please provide me your airport codes.

USER: My airport codes from DEN to JFK.

ASSISTANT: Do you have any class preferences?

USER: No.

ASSISTANT: Is there any time concern?

USER: Yes, I want to return in the evening.

ASSISTANT: Ok, do you need any break in between your journey?

USER: No.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Sorry, I did not find any flights for you.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you for reaching us.