Tim,
Not sure if Im getting the full gist of your JB problem but if I’m understanding you correctly, I would call back and explain the situation slowly and clearly once again, and if the CSR who takes your call can’t make it right I would then ask to speak with a supervisor.
If you were booked on a flight and selected seats as part if your transaction, unless the equipment was changed and/or the flight was totally cancelled, once you were booked there should NOThave been changes made. And if you actually bought JB points in a cash transaction I would think they have an absolute responsibility to get you back on your original flight.
Again, that’s IF I’m understanding what has happened with your reservation.