@StormyCA, I, too, just got off the phone with a Disney CM, and she said the same thing re: MP. She had no idea about price increases, and she also indicated that I could not add MP to my package. Becky-the-CM said we need to add them via the DL app when we go through the turnstile when we enter the park for the first time.
I went ahead and added a 3rd park hopper day to our package; we've been debating for a while, and I didn't want to risk a price increase. We are one step closer to our trip in July. Getting so excited!!