Jody Cussins

I have replaced the rotors to drilled and slotted with comparable pads. My lines have burst twice and been repaired. I've had the master cyl. replaced and lines flushed and bled numerous times but I can't get any more pedal. Someone said I need to replace the booster now. Can someone give me any ideas of what to do next? I'm about out of ideas. the truck only has 59 k miles on it.