Bleaching is a term that is broadly used in our hobby and refers to many things. It can be from stress where a coral releases its zooxanthellae algae leaving the coral white in color. it can be from lack of nutrients, too much light, etc. All coral (animals) have the ability to display this whiting out look you refer to. I suggest you find a new LFS.
As far as your current piece. Get it to a medium light area, with medium flow and feed when possible. Test your params and keep them within recommended levels. If the tissue is gone from a spot, it is really tough to recover on a goni/alveo IME.