Despite the very low 28mpg is very poor, you should at least be getting mid to high 30mpg, the VW 150 bhp is a very efficient fuel engine particularly combined with the 7 speed DSG transmission.
Virtually straight out the dealers showroom with less than 300 mile our Ford Kuga 150 bhp diesel powershift towing a 1450 kg caravan was returning similar figures to your 28 mpg and 40+ solo, the VW engine is more fuel efficient than the Ford/Peugeot/Citroen.
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.