There were hundreds of these cases, and the affect post-masters were calling the IT helpline repeatedly saying sums of money were going missing. Personally I think that if you have hundreds of people of good reputation and standing swearing up and down that they didn't steal money, and there's a record of their having called repeatedly to report erroneous data in the software, then there should be some sort of investigation to figure out what was going on. Instead they were shouted down and threatened.