I can't see your pics, but from similar experience can tell you to prune out the dead wood now. Plants will come back; mine have, to be fuller than ever. In my garden most of the damage I get to heather comes in early spring, after I uncover them to shear their tops, which is a yearly must, in March. I have learned to then replace their covering of evergreen boughs until mid to late April, when the danger of sun scald seems to pass.

I had a problem of a different sort, though, in their first spring in my garden: a fungal disease. I watered them throughly (twice, two weeks apart) with a systemic fungicide and pruned out the dead wood. Those affected recovered very well. I follow this practice once a year, just as they begin new growth.

I have read that one or two light foliar feedings during the growing season will aid new growth on affected plants. (I didn't do this.) Once the plants recover, though, cease the feeding; Calluna don't respond well to high fertility. (Don't feed healthy plants.)

Watering. Don't let their beds dry out; mulch until plants are well established. Keep the mulch 2" away from their bases; and always water in the mornings. Aim for dry mulch but slightly moist soil, but not wet! Excellent drainage and acidic soil are musts.

My heather has turned all brown - should I just cut back and hope for the best?