Hello Peter! Wow! A 20-night package to visit the Most Magical Place on Earth! You’re going to have plenty of time to enjoy all that the Walt Disney World Resort has to offer!
Regarding your tickets, I believe what you were told is correct. You should be able to select the start date for your tickets during your vacation time frame. Theme park tickets usually have an expiration date but are eligible to start the first day that you enter a Disney Park. You are definitely able to use your tickets on non-consecutive days throughout your vacation. Just be sure to make a
Disney Park Pass reservation for the days that you want to visit the parks.
Peter, if you purchased your tickets through an independent agency, then I recommend calling the agent with whom you booked your tickets. If you booked through the Walt Disney World Resort, I recommend calling a Cast Member. The number to call for
existing ticket questions is (407)-934-7639. A friendly and knowledgeable Cast Member will be able to provide you with the specific manner in which you can adjust the stated dates of your tickets! Don't worry, Peter! You are asking the right questions with plenty of time before your visit to get the dates corrected!
Hakuna Matata! Jonathan