I fixed a high spot similar to this one time by cutting an "X" in the bump with a cutting wheel, then hammering it down flat, then mig welding the "X" slowly with a series of small tacks. The weld will shrink as it cools which will pull the metal tight. It wasn't perfect but it was good enough for an amature like me. After putting a skim coat of filler and sanding, you couldn't see it. Just a thought.......
