Key legal question
Whether the insured had to restitute the undue payment despite invoking good faith.
Extracted holding
Yes. The insured was not acting in good faith because he knew he was entitled only to a monthly pension, so restitution of the undue amount was required.
Extracted reasoning
Good faith cannot be relied on when the recipient knows the payment is not owed. The monthly pension entitlement made the lump-sum receipt evidently incorrect.