Yes, I is still discounted Business class but not as discounted as R.

I9 across the board - means the airline is will to sell at least 9 seats in I class on every flight. Your agent should have had no trouble in rebooking you to a preferred flight.

I agree with @Often1 , there is something fishy here given "the agent is saying she is trying to change it but cannot as its very busy".

It is not "busy".