First, these may have been the plumber’s mistakes in measuring where the pipe were supposed to be, they could also be the builder’s error by making changes and not relaying those changes to the plumber.
The only solution is to cut out and remove some of the slab and dig out the soil to expose where the pipes are, and where the pipes are supposed to be, so the pipes can be rerouted. After the plumbing work is redone, the soil fill needs to be re-compacted (not just thrown into the openings and stepped on), then the compacted soil needs to be re-pretreated for termites as the original pretreatment was disturbed and dug out, the a moisture barrier needs to be installed over the exposed soil and tucked up under the sides of the slab around the openings, then holes fore dowels need to be drilled into the edge of the surrounding slab, next welded wire mesh (WWM) needs to be laid in the openings, the steel rebar dowels needs to be epoxy set into the drilled holes, then finally the concrete for the slab can be poured into the openings.
I know of no other solution. This occurs all to often and the usual repair amounts to throwing dirt and rubble / debris back into the holes and then pouring full of concrete. As you can from the above paragraph, there is more to making a proper repair than just this.