Try this site and article.
http://www.classicshaving.com/articl...0351/18187.htm
I suffered for years with with the samething in my neck area, not to the extent that you do. I found this site and bought a cheap wal mart brush and soap. No more problems. I can shave and have no stubble and no irritation. I have been using a brush and soap for over a year now. I used a regular disposible razor for most of that time, I just recently switched to the old safety razor style, it takes alot more work to get a close shave. I tell you this because on the website they tell you that a safety razor is better.
Give it a try and see if it helps.
The shave soap is the most important in my opinion, the brush is the second.