WHAT????? I think this is outrageous. Get ready for a fight.

In the days of lazer sharpness he should have aligned the new wall with the old wall. If they are aligned then there must be something under the drywall holding it up at that one point. Did you get photos of the wall before the drywall went up? Did you ask him WHY it has to be that way? I would not accept his answer or the wall. It would drive me crazy looking at it over the years.

A good contractor would have anticipated this problem, if not at the very start of the project then at least at a pretty early point. He should have discussed it with you, letting you know that there would be some (perhaps significant) expense in getting it right.

It's impossible for the rest of us to know how this situation evolved. Did you take the lowest bidder?

Most contractors I know don't like to leave ugly eyesores behind on their work. They want to do good work and have happy clients. Sometimes even the best tradesmen feel they are getting paid only enough to do the quickest and dirtiest job possible and they won't spend a minute longer than they have to on a job. You need to be honest with yourself. Was the fee charged adequate for a first class job or no?

I'm not a pro. I'm just a regular diy homeowner, and my difficult match ups look better than this. The section that is recessed should have been shimmed it to match up with the old section or at the very least built up and blended in with the protruding side. You should expect this to be fixed. This is not normal at all and anything can be made to look right of the contractor cares enough to bother, but sadly he doesn't consider it worth his time.

I do hope that you are not going to accept this. There is absolutely no excuse no matter who you hired.