If you are entering your order via the computer their software can direct it anywhere they want. The best place to do business is at the primary Exchange of PRB's listing, the TSXV. The next time you want to enter an order I would suggest calling it in to the special handling desk and direct it to the TSXV. The only drawback is they may up your commission for special handling.
I have been dealing with brokerage firms since I was in high school and over that time period I have noticed some changes with some, they seem to be more income oriented as opposed to customer oriented. Just like new brokers are taught to know their customers, customers, as well, should know the brokerage firms they have selected to service them.