You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Charles Parker. I want to change my flight reservation, can you please help me?

ASSISTANT: Sure, please give me a moment.

USER: Sure.

ASSISTANT: I found your reservation, please provide your rescheduled itinerary dates.

USER: I would like to depart on Mar 31st and I will return in the evening on Apr 2nd.

ASSISTANT: May I know your airport codes?

USER: I want to travel from CLT to OAK.

ASSISTANT: Do you have any specifications?

USER: I need single connection flight for my journey.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, no flights are available on your route.

USER: Oh! Not an issue, thank you for the information.

ASSISTANT: Thank you for reaching us.