Can't say it any better than Chombi did, but...it sounds like it may be just the part of the caliper arm that holds the brake shoe might be tweaked out a bit. If so, you can probably save it. Take the brake apart, hold affected arm in a vise with padded jaws, if available, and tweak the slotted pad holder portion back to straight with the jaws of an 8 or 10 inch adjustable wrench tightly clamped to the flats on the arm. The trick will be going exactly the amount and direction you need. Like Chombi sez, one bend is, ideally, all you get, and good advance planning will help a lot. No heat. Doesn't help much with forged aluminum. Good luck. Worth trying. You might even be able to accomplish it with the caliper still mounted to the bike.