Having worked in revenue assurance I can unerstand why the bank is asking the customers to come to them. In the end they are probably struggling to identify who has been effected by the glitch. Some they can detect and correct. The rest they are depending on the customer to tell them. If they attempted to fix all the accounts automatically, they would no doubt find themslves changing more accounts than they needed to. The end result is an even worse mess.
The old adage comes to mind: When you're in a hole, stop digging.
In this case better to under-correct and ask the customers to tell you of any problems left over, than to over-correct and have even more customers effected. It could even have got to the point that the bank didn't have a clue what was in the accounts if they made too many adjustment attempts.
In the end, my sympathy to the poor IT sods beavering away to correct this problem.
