Left Disc DRAGS...??????

Jack it up , pump the brake, turn the wheel by hand and feel for the drag.
Crack the bleeder and feel for change. Still tight rules out lines, etc...
Check the pads for binding in their guides. I've found stamped backing plates that needed filing more than once. Quality control aint what it once was. nothing left but caliper to blame ( and your mechanic ) . Always replace calipers in pairs.