The tung oil was just a cheap easy way (to me) to protect any uncovered wood on the guitar. If you have a luthier nearby, maybe he could give you some price options to refinish. At the least, you might be able to get an idea what the problems are and what kind of finish it is. Then you can decide if you want to have a go at it yourself or pay up or maybe decide you like the weathered look :)

Here is a link to Project Guitar forum acoustic section. You can fine out pretty much anything you need to know from some real experts. Be prepared to supply pictures.
http://projectguitar.ibforums.com/index.php?showforum=14