The important question here is “why does it matter?” Your broker trading against you has nothing to do with your success… I’ve never seen anyone produce any evidence of brokers manipulating trades.
I would think that you are correct with you assumption, given that around 95% of people lose whilst trading i would have thought that your broker would be only too chuffed to accept your trade in the almost certain knowledge that you will lose!
From what i understand this is how it goes. Brokers know that a very large % of traders blow their accounts, they know what kind of traders loose their money, so if the way you trade falls under the category of what they believe to be a loosing trader, they trade against you! And why would’nt they, they know that they have the odds on their side, all they have to do is keep trading against who they believe will be a loosing trader and eventully they will profit, just like how casinos work they know that the %'s of each of their games are in their favour so all they have to do is open the doors and keep spinning the wheel, rolling the dice, and dealing the cards, and by the end of the day they will take profit.
I don’t think brokers mess around with their charts, and if there were any brokers messing around they would be quickly found out.