93 alarm ok trans-not ok

recently brought my full time quadra trac JGC laredo 5.2, 151,000mi. in for a basic tune up/ check-up at a local repair shop. The mechanic found that the front diff was shot, so he removed some torn up pieces, disconnected something that made my jeep 2wd only. He said this would not hurt the transmission none. He also changed the gasket and tranny fluid from the pan (aprx 3 quarts). When I got the car back, after a day or two with low miles driven, I heard funny metal grinding and sweaking. It sounded like gears with no lubrication getting ruined. I checked my Tranny fluid, and it was barely showing on the stick. I added three quarts before the level was right. There were no leaks or puddles under the car, leading me to believe that the mechanic forgot to add the tranny fluid after he did the gasket. I brought it back a day or two after that because the tranny had started slipping. Naturally, they said it was the Tranny, and that it had nothing to do with the front diff or the three quarts it was missing, and it was coincidence that this happened immediatly after getting the car back. Any ideas about this? How can I go about getting them to make good on this?

The Quadra-tra system is a full time 4wd system which means it needs to be in 4wd at all times. The transfer case has clutches in it like a locker in your diff would have. So in taking the front drive shaft out the clutches dont work like they should. Which could throw the tranny off too. But the three quarts low doesnt help!!