You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what kind of service are you looking for?

USER: I would like change my recent reservation due to some personal issues, will you help me with that?

ASSISTANT: Sure, I will help you with it.

USER: Thank you for accepting my request.

ASSISTANT: To check your existing reservation I need your name, can you please share it with me?

USER: Myself Nancy Johnson.

ASSISTANT: Please wait, I will fetch your current reservation and revert back to you shortly.

USER: Sure, I will wait.

ASSISTANT: We have found your reservation, can you please share your updated source and destination airport codes?

USER: My airport codes are PHL and SFO.

ASSISTANT: May I know your dates of travelling to move forward with the booking?

USER: My travelling dates are Sept 15 and Sept 17.

ASSISTANT: To make your journey more comfortable do you prefer any specific class?

USER: I am comfortable in any class.

ASSISTANT: Is a connecting flight works for you?

USER: I need a flight with single connection.

ASSISTANT: Ok, do you prefer any particular airline?

USER: No, I don't have any other specifications.

ASSISTANT: Do you have any time limitation for your departure and arrival?

USER: No, thank you.

ASSISTANT: Thank you for being patient and providing all the details, please wait for a while.

USER: Ok, I will wait for your response.

ASSISTANT: I am sorry to inform you that we don't have any flight available which meets your journey criteria.

USER: Ok, not an issue. Thank you for your information,.

ASSISTANT: Thank you for checking it with us, we hope to serve you better next time.