i feel for you. we have a well & septic, whole house back flush carbon filter for iron and particles, water softener and reverse osmosis for drinking/ice maker. spring thaw is the worst, the whole neighborhood complains about water quality. ro does take up to 10 gallons of back flush to produce one gallon of ro water, thou your system sound like it's well past that.
you probably have a bad unit or hooked up incorrectly, even if you checked 10x. have you tried manufacturers tech support yet? they're pretty good with their own product. they may even send you a new unit or control body.
we've used ro for over 20 years with very good results. the city recently ran a 12" water main down the road, i'd never change over to city water, because of the monthly cost. water bills can run over $300 per quarter without lawn sprinkler systems.