1999 Chevy Blazer Brakes Locking up

I recently had a broken brake hose on the right front wheel of my 99 Chevy Blazer. I had the hose replaced at a repair shop and they had bleed the caliper only on the wheel that the hose was replace on. The brakes seemed like they were back to normal after the hose was replaced, but I noticed that after I drive the vehicle for about 10 to 15 minutes and the car has warmed up the brakes start to lock up. It feels as though I am driving and pressing down on the brake pedal at the same time. When I come to a stop usually the care will roll if I take my foot off the brake pedal, but once the car warms up and I take my foot off the brake pedal it will not move. If I let the car sit and cool down for about an hour or overnight it is fine for about 15 minutes and then the brakes start to lock up again. I have also noticed that the brake pedal seems to get much harder as the car warms up and it seems as though the ABS is not functioning properly even though the ABS light is not on. When the car is cold the brake pedal feels normal. I brought it back to the mechanic who installed the new hose and he is telling me that the problem is with the calipers and the booster and with nothing that they did. I didn't have any problems with the brakes except for a cracked hose before they did any work on the vehicle. He now wants a ridiculus amount of money to repair the problem and he says that there is no guarantee that changing the calipers and the booster will solve this problem and that it can also be a defective master cylinder! Does anyone have any ideas of why the brake systen is building up pressure and causing the brakes to lock up on their own? Please help!