What happened was they were supplied with an accounting software with a glitch that caused a discrepancy between the transactions and the turnover, it would make the post master appear as if they were embezzling some of the income from the post office.
To cut a long story short, hundreds of Post masters were taken to court and wrongfully sent to prison for fraud. As far as I know, it was one of the biggest miscarriages of justice in British History. Some of the post masters were fired, others were Jailed, many of them committed suicide. Some of them had their personal property taken away from them. Many of the post masters went through a divorce and a living hell.
I recently learned that many of the post Masters still haven't got their compensation for the Post office software glitch. When they were pardoned, they sued the Post office for damages but are still waiting.
There is nothing to be proud of in this world when you think about it, we are only one cancer cell away from a slow painful death. We are only a glitch away from a living hell. When we die we have no possessions, we don't even know if we can keep our minds and memories when our bodies are gone. We know very little.