If the areas which are dying off correspond to ants' nests beneath, then very likely - their activity prevents the turf from rooting into the soil. You can get water on nematode solutions for killing off ants, part of the Nemesys range, but otherwise, peel back the turf in those areas, open up and run away, then come back with a kettle full of boiling water and pour into the open nest. If you're wearing boots or wellies, have the kettleful ready for pouring as soon as you've opened it up.