This reminds me of work at a client where there were some issues. The code introduced a bug that causes all refunds to change to charges during settlement. Whe

This reminds me of work at a client where there were some issues. The code introduced a bug that causes all refunds to change to charges during settlement. When someone called in pissed and wanted a refund they'd be charged again 2 days later. There was also an issue with an account transfer into their system where the mapping hadn't entirely been completed. They imported a bunch of subscriptions with their last billed date but didn't properly mark the status of the subscription. The system retried the rebills for some users back four years ago and tried to auth every month for the last four years for some users.