Walls and Ceilings - Help, outlet holes cut too large!!

I had another room added onto an existing one. The guy that did the drywall cut almost all the outlet and switch box holes too big. Some are as much as an inch. I don't know what to do. I didn't really notice until I was done painting and tried to put the covers on. Unfortunately I think the guy is a flake and left town. I have no idea what to do. I thought about filling with spackle filler but some of the switch plates are for three switches which makes it a pretty long opening to spackle. I would appreciate suggestions. I hope I don't have to have the drywall replaced after I've painted it all! :confused:

you can get oversized switch plates and receptacle covers at any Lowes or Home Depot.