Essentially, they're not learning from their mistakes, they're not listening to the advice they ask for. Making mistakes is an important part of the learning process, if you learn from your mistakes, make notes if required, and move on.
The current situation with out client sees none of this happening. It can be quite annoying when such problems get classed as 'high priority' (in this case, help with someone else's problems in addition to our own work load) and good advice, investigation/working practices suggested get ignored.
There may be a light at the end of the tunnel, with many failures they should have caught making their way into the production systems the problems have been escalated with the client, and a more senior (objective and level headed) manager assigned to the task. Perhaps he'll whip their team back into shape.
Signing off with 'Fail and fail often' by Jeri Ellsworth. Fantastic advice, applicable to more than electronics.