How do I reinforce a metal shelf on a concrete wall when it's anchors are coming lose?

In our storeroom we have a metal shelf fixed to a concrete wall and whoever hanged it used plastic anchors. I know this was a stupid mistake, but now I've got the problem that the anchors are coming out and has taken a little of the wall surrounding them with it. I don't have the room to hang it higher or lower or to the side. We do, however, really need this shelf. Is there still a fix it to the wall properly?