Re-prepping to paint

The prior paint job was not done right. On sections under the windows on both sides of the truck the paint was overdone leaving raised spots and runs. It's white and really only noticeable to shadow and someone with a trained eye. Also in one section the overpainted left diagonal streaks. Do I have to reprep the area or will repainting by a real professional make this problem solve itself? Any help will be greatly appreciated. I want this to be done right the second time! B.