Not familiar with what "FPL" is and not sure what you mean "big hole in the center of her branches". Do you have photos you can upload?

FPL = Florida Power & Light.

Asplundh most likely did the trimming.

Probably had power lines above so they trimmed away the middle portion under the lines, so it now has a Y shape.

I've seen some pretty horrendous trimming jobs under the power lines done by them,

I see what you mean. I've seen it done before, but not to Mangos. Trees and power lines don't mix well. It's unfortunate the tree was planted directly below, not the brightest idea on someone's part. As far as the tree goes there's no real problem, if the cutting was done correctly. Mangos can take a very severe pruning and just carry on regardless. There could be an issue if fungus or other plant pathogens get in and start weakening the inside of the tree. That could make large upper limbs collapse, especially in cyclonic weather. If you can get some grafting paint and paint over the exposed wood it would help seal it against the entry of anything unwanted. I use grafting paint because it's readily available here, it's antiseptic and is designed to protect. The tree will then be able to grow over the cut surfaces covering them completely. But you have to remember, the power and light people will keep coming back and keep cutting. And you don't want to have anyone trying to get fruit that's hanging close to live power lines. Long term prognosis is not good. Probably a good idea to get yourself another tree, plant it well away from power lines, and when the time comes for the "old timer" to move on to the big mango plantation in the sky you'll have a well advance youngster.