I have to say the only time I've been in to Bournemouth, for Proj Propeller, I was handled by Bournemouth Handling and they were great. But, I didn't have to pay for it as they donated the free handling in aid of the charity. I'm not sure I'd have been that happy to pay.
Interesting question as to the legality; I suspect that it needs challenging in court if there is no choice of handler.
Tim