When logged into your SweepSouth account, visit: https://sweepsouth.com/accounts/profile/vouchers/. Add your voucher code to the space provided and click on 'Redeem Gift Voucher', we will then confirm the success of the redemption. This credit will now be added to your SweepCred balance which you will be able to view here: https://sweepsouth.com/accounts/profile/sweepcred/.
Note that gift vouchers may only be redeemed via the website and not via the app.