LPM
Sorry but cannot see the problem? They fork out a wad of notes for your recurrent and you leave the following week?
You give them six months service and then leave why shouldnt they ask for the other half they have paid for back?
Its a way of them showing they are committed to you and expecting you to be committed to them. Frankly unless you up and leave to work for someone else I cannot see your gripe as it would not be an issue.
If you did up and leave maybe they have a moral right to bill the next employer for something they have paid for.
Pace