The digiboxes cost more like £300. The problems of customers defaulting is real and yes it is happening much less now with the new credit policy. Sales staff turnover is still very high and some fairly senior field sales supervisors have had the chop recently with at least one suspended that I know of. No names no pack drill!
Until tw change the way they sell the products ( Which are very good imho )they will not regain any customer confidence, which at the end of the day is what will drive forward business.
Even big deposits are no good if you then let customers run up bills larger than the deposit!
Once every old analogue box is gone they will get rid of another problem too, ie the chipped boxes. Also analogue uses up far more bandwidth than digi.