Loading the black pill flashes it over to cricket, you still have to unlock it. If you only paid $50 you probably didn't get it fully unlocked. on the right side of the phone hold down the power (top) button and the Camera (lower) button at the same time while pressing soft reset the little hole in the bottom of the phone to see if there is an unlocker installed. if its not unlocked it still needs to be unlocked to install the black pill. (press the soft reset again to take it out of the rainbow screen)
All they probably did for you was load the 1050 PRL so you could make calls on the cricket network. Which takes maybe 30 seconds.
At any rate here is the link to vetvitos black pill its the 3rd one down
http://forum.ppcgeeks.com/showthread.php?t=18836