Trying to wrap my head around all of this.

My son and his friends have reservations for POP July 4 and Julyl 5-10. (The 5th-10 has the hoppers and
free dining attached. 4th was an afterthought added later- room only) I haven't cancelled in hopes of rescheduling their trip. (All going off to college in late Aug- so it's early Aug or end of Dec/Jan. No other options). So- no parks open during their dates. Shocked that they weren't cancelled outright. They want to reschedule- I've been waiting for the green light from Disney to contact them.
Tonight's email says they need to
confirm, modify, or cancel their reservation by June 12. (I am guessing this is referring to the July 4th reservation because it falls in the 6/22-7/4 window). I've been on hold for 55 min now- and keep getting the same recording saying that they
cannot modify reservations at this time. I'm a little confused here. Can they modify reservations or not? Why are they saying I need to confirm, modify, or cancel if they can't modify? (Am I sitting on hold for no reason?)