Bataille Empire

Had an Austrian unit retire disordered behind a supporting unit
In the next turn I want to pull it back 6UD
DO I have to pay the cost for a B class unit turning around?

I can find nothing to suggest there is any avoiding the cost of formation changes when disordered. The move is at column speed, presumably because there is no slowing down to keep in formation.
There would be a good argument for making it more difficult to get disordered troops to do anything in the way of manoeuvring.

We've been moving them like unformed skirmisher units - 6 UD pretty mu in any direction.

Not sure it is helpful but we've been saying that they retain the facing and similar rules, so if they want to retreat its pay for the turn and go back. Also means that you can hit the flank or rear which is painful when it happens (or fun if you are the attacker)