Eliminating An Instrument From An Audio File

I'm trying to do a favor for a young lady in Pakistan. I offered to clean up the recording and add some instruments. For the past few hours I've tried nearly every plugin in Sonar to get rid of the acoustic guitar in this file. I realize that a steel string acoustic and the inherent harmonics make it nearly impossible to isolate and crush the sound without also hurting the vocal. However, there are some pretty smart folks on this forum.
 
I was trying to get most of the guitar out, increasing whatever vocal was left, and then combining the two tracks in Sonar. The results have been rather dismal.
 
If you can do it, please email me the Sonar project file and I would be extremely grateful. (terrydelaney@outlook.com) I've been trying to get her to send me a pure vocal track, but like I say, she's in Pakistan. Not exactly the hub of the music industry.
 
(The file is in WMA format for ease of downloading. The original is in a standard 44.1 WAV format.)

I am on my cell now, but if they are panned the same (both centered), the frequency ranges can overlap enough to make this extremely difficult. R-Mix (from X2) may not cut it either (no pan or frequency separation).

I chimed in on this so I remember to check it out when I can. Do not get to hopeful of such things (is often better to bite the bullet and retrack them).

Have her record over the existing track at a soft whisper, with the shower running, the words bomb, jihad, terrorist cell. When the NSA finds this track inbound from Pakistan, they will use the kind of technology you need to pull out the vocal. Getting the resulting clean track from them will be the next problem.

Yeah, looks like she's gonna have to do what mettalus is suggesting. She usually visits her alma mater here in Boise, Idaho once or twice a year, so I'll grab her and get her into my studio.
 
@slartabartfast: I read an article somewhere that claimed the NSA can isolate a single conversation from a noisy crowd. Seems impossible to me, but I'm just a hack keyboardist.

Hehe, the REAL solution