I bought a Fender American Special Jazz Bass under 2 years ago (still under warranty I believe). I play it only occasionally, as work/family take their toll on spare time. One thing that drives me crazy is on the back of the neck there is a rough patch, you can't see it, but you can feel it isn't nice and smooth like the rest of the neck. Ironically, my cheap Ibanez bass I replaced with this has a perfect finish on the back of the neck.

Now, I've brought it to 2 guitar shop repair guys, one from the store which I purchased it from. Both thought it was a bit of over-spray. They said they 'smoothed' it, "Just needed a little bit of smoothing" to quote one of them. When they hand it back to me, it feels perfect, but then a day or so later the rough patch comes back!

I don't know what to do at this point. I can't keep getting these guys to 'smooth' it, what a pain that would be. I'm looking for a permanent solution here. I can:

(1) Send it out to have it sanded and refinished (maybe that's overkill).
(2) Smooth it myself, assuming that this only needs to be done a couple more times to permanently fix the issue (bear in mind I'm not DIY pro).
(3) Sell the bass off and buy something else (Unfortunately, it bothers me that much).

Here's what I got:

The neck has a 'Satin Urethane' finish. If I try 'smoothing' it myself with a green 3M scratch pad or similar, I don't want to ruin it. Certainly apprehensive to fix this myself.

Thanks in advanced for any advice!
It sounds as though what LovroMirnik is saying will most definitely void the warranty. he may be correct though, I am not sure. I would take it back to the store you bought it from and tell them and try and claim it under warranty and get a replacement. It might be a long shot, but fight for it. Worth a shot.
Could be a tough one. If it is indeed a materials/manufacturing defect then it should be covered by Fender's Limited Lifetime Warranty, but you've had it a couple of years now and trying to get around the exclusion clause that says the warranty won't cover damage to finishes caused by abuse, bodily fluids, non-approved cleaners, etc, etc, might be an uphill battle...
I wouldn't suggest using 1200 grit dry. The finish dust will clump to the the sand paper and gouge the finish and leave scratches. I would recommend white scotch bright and go over it lightly. I'm guessing when the shop "smoothed" it they probably just applied some polish to it and it wore off from you playing. I use white scotch bright on a couple of my guitars with natural finishes to keep them smooth. Good luck keep us posted.