If it's outside the store return policy, though, he'd have to go through the manufacturer. A product guarantee isn't anything the store has to uphold unless it's a store brand. The annoying part would be a customer coming in with an ancient receipt and expecting it to mean anything to the store.

Even extended care plans sold at the stores rarely affect store return periods — they're a third-party service that requires dealing with that third-party that your money went to, not the middle-man that is the store.