If you received a notification that your flight has been changed to another one, it means that the airline has canceled your original flight and offered an alternative, usually the next available one in the schedule.

The ticket needs to be reissued. You can agree to the new option or contact our specialists to find a more convenient flight with the same airline.

If none of the alternatives suit you, request an involuntary ticket refund.

You can send a request to customer support for an exchange or refund of your ticket on the order page. 

I received two messages: one states that the ticket does not need to be reissued, and the other states that it does. I can't figure it out.