Bathtub faucet

I have recently returned to a house that I have been renting out for seven years. During that time, my rental agent has had a local plumber work on my bathtub faucet four times. It still leaks. It is obvious that all they have been doing is replacing the o-ring and the stem (so they say). You could feel the fatness of the o-ring when you shut off the flow, but now it appears that the ring has been cut through again and the faucet is leaking. The bathtub is tiled over drywall and I hate to have someone tear into it, but Im really getting tired of paying someone to do temporary fixes. Is there any way to replace faucet handles (two faucets on either side of a spigot)completely without opening a huge hole? Also, since the faucet is leaking now and I would like to buy some time to shop around for fixtures, how hard is it for a novice to stick another o-ring in for a quick fix? Any help is appreciated.Keith Watson