Betting to win and laying the place

I mean will it negate the premium charge if you could develop a winning strategy or will it greatly reduce the amount due, due to the amount of commission that you are already paying?

unless the horse fills one of the other places

if your a PC payer, how can you possibly make this statement without realising you will sometimes lose both - and therefore the likelihood is that you will reduce your PC, but increase your loss by more than you save!

I'd suggest a better way would be to find 2 markets where you cannot lose ( ie 0-0 and next goal in a footie match) where you might find a better price on one that may make you a tiny overall profit  -  however, the comm will most likely kill you, even if you find an edge