Unfortunately, OP paid with points, not cash and therefore, all a chargeback will get him is any portion of the ticket, such as taxes, paid with cash.

I would nonetheless initiate a chargeback with your card issuer for any cash portion of the ticket, providing a copy of the relevant contract provision (above) as well as the fact that SA has refused to honor its contract.

I would then write to Chase, noting that SA has a contractual obligation to refund and that Chase, as its business partner, has an obligation to force the issue. Doubt this gets you far, but it is the risk of not paying with a card.