Oldsmobile/Buick Repair: front brakes lock, buick roadmaster, 1994 buick roadmaster

Question
I had a master cylinder replace on my car, then some lines got broke, and they were repair. I was told I needed back brake drums, so that was done and the rotors turned.  Soon after, the front brakes started to lock, smoke, drag and I had calipers put on the back, and the passenger front cylinder replaced, they locked again, so a new hose to the brake line was put on the front.  During this time, a film of some sort was noticed on top of my brake fluid box, and the diagrahm was spongy and gummy.  I was told it looked like someone had put something beside brake fluid in, but the slime was taken off, and the diagram was replaced.  The brake light is on, I am told there is not any  fluid going to the brakes, the front brakes are still locking. The repairer contacted General motors, performed whatever they said to do, and have now returned my auto as they do not know what is wrong with the brakes.  The auto is a 1994 Buick Roadmaster Estate Wagon, and I do not know what to do, or who to take it to, or have any ideal if I can afford this kind of repair bill.  Please advise me.  There is not brake fluid going into my back brakes, but the front ones do work some, but lock.

Thank you

Answer
hi betty.wow what a streak of bad luck.i guess the bulk of your prob is you have no fluid going to rear brakes.brakes today are much more complicated then they used to be.there is a valve located under your car normally located under the drivers side where the frame bends mounted to the frame.this is called a proportioning valve.it,s job is to make sure equal amounts of fluid goes to each wheel to maintain proper pressure at calipers..now this valve has a safety valve in case of sudden pressure loss  such as a line blowing out.it stops the flow of fluid accordingly to front or rear.these valves are supposed to restore fluid as soon as leak is repaired.but sometimes they go bad and will not reset if so replacement of this part is required.the part and replacement should not be over 100 .00.but there is a bleeding sequence they can try first.the normal bleed system is to bleed wheel farthest from the master.but for this first bleed left front and the right front then left rear.then r rear.this procedure normally will restore fluid. but first have them brake one line loose at master cyl be sure fluid is there if so retighten that line and brake the other lines at master one at a time.and should have pressure at all lines at master.if not replace master.even though new still can be defective.if fluid is ok at master try this bleed procedure if not replace proportion valve..hope this helps you betty.billy mac