circumstances alter cases
Unique circumstances can spur unconventional action. I know offering such a big refund isn't protocol, but it's for the CEO's grandmother, and circumstances alter cases.
Circumstances alter cases.
Prov. In unusual situations, people are allowed to do unusual things. Cashier: I'm sorry, this store does not accept personal checks. Customer: But I need this medicine, and I don't have any cash. I've shopped at this store for fifteen years. Surely you can trust me this once. Cashier: Well, all right. Circumstances alter cases.