Never heard of Barums (though they are made in Czech republic), but 5000 miles is plainly stupid.
For a bit more money invest in Falkens. I had a new set all around and since done just under 5000, and seem to be fine, with (I reckon) at least another 15K in them (if not more).
What pressure have you been running at. I use 35PSI (as recommended in the Mk4 owners guide) also ran this pressure on previous LS.
You could also try Nexen's they are hard wearing, cheaper than Falkens, but tramline like mad on motorways
As to the rear coil spring, does sound a little over the top, though I am aware from experience with the good lady's motor, that £250 seems to be the number any dealer quotes for anything like this, and you have to haggle.