PRS availibility is the same as what is displayed on IRCTC, and don't think visiting PRS counter can solve this. From what I can see is that there are 2 berths available in 2A and 44 in 3A and 0 in either class LB Quota. In short, 3 berths together are not available and thus the problem.
This is a common problem experienced by group/family travellers and the amount of money wasted in booking/cancellation when seats are not obtained as per one's choice. IR could consider not to allocate coach/seat number, just like 1A/FC during booking, but allocate them at final charting thus solving this huge problem.