Im not familiar with GVRP....so what you are telling me is that the brokerage will buy a stock for me, take my money for it....have it show up in my account, then say, "Sorry, we decided to not let you have those shares afterall...and oh, yeah, we'll be keeping the money you paid for them.
Not a chance this would happen. Every brokerage firm that did that would be sued and shut down forthwith.