Can you post a picture of the tree? From what I can gather it sounds like you're trying to turn a "dragon trunk" into a straight trunk. And I've read this thread really just shaking my head because that's not something that's going to be accomplished without years of training on a main trunk. The new grwoth will have to lignify, and the layered growth season to season of the new growth will have to be stronger than the old growth in order to resist its attempt to return to its former shape.
That can definitely be fixed with either a bender or some pretty thick wire. Both are likely to scar, though. IMO, it's not bad and lends character to the tree. I'd work with it rather than against it (which is often the best/easiest case). Doing so can very often lead to surprising, interesting, and pleasant results.