Could Sub-Postmasters Have Escalated or Disputed Effectively?

What if a software bug drained your savings, ruined your reputation, and nobody believed it wasn't your fault?

 Scott Darlington took over a village post office, hoping to give his family a steady life. But the software system kept showing cash shortfalls he couldn't explain. Each time, the Post Office told him the numbers were right and made him pay the difference out of his own pocket.

 Eventually it became too much and actions Scott took to protect himself lead to his arrest and public shaming. 

 How do you build trust in systems when the people behind them refuse to admit they're broken?