Reading between the lines, it sounds like you have (Shimano) V-brakes all around. The front left arm is chronically not retracting enough to pull the brake pad away from the wheel. Your LBS has repeatedly tried and failed to fix this. Correct?
1: Buy a better grade of V-brake. The better ones really do move better.
2: It is possible the attaching bolt is pinching the left V-brake keeping it from moving freely. The pivot boss on the fork could be a tiny bit short. Or, the mounting hardware has gotten damaged: I once encountered a cantilever brake (different brake, bit same result) that used soft metal washers under the heads of the attaching bolts. One of the bolts had been tightened so much that the pivot boss had pressed into the washer. The result was that the brake arm was getting pinched.