See if we have the same problem ... My Starex' seat was very uncomfortable. I thought it was ok at first, then I started getting back pains. Later, it came to a point where it was very painful and I needed massage every night, else I couldn't sleep. I finally narrowed it down to the seat as the culprit. My options were: 1) have a seat cover that alters the contour (low probability of working), 2) change seat to an adjustable type (high probability, expensive at P24k to P35k), 3) change the car.

My solution was to get another car w/ an adjustable seat. Pain went away. Every now and then, I'd drive the Starex but limit it to short driving, else some back irritation starts to creep again.