Takelot and Give Numerous Issues in Return

My wife orders and pays for 3 items (***). Shipping details mention only 2 items and upon enquiry she's told the 3rd item is out of stock and she'd have a credit. She insists on a refund as a store CANNOT take your money for what they don't have and keep it 'till a PRESUMED 'next time'. Horlin apologises and says the refund will be made. Weeks later, my wife 'tries' another transaction. The credit still reflects, so it was never refunded. All well, 'cause the system says it will now be deducted from this order (***). That doesn't happen! She pays in part with e-bucks and wants to pay the balance with debit card. On the app, credit card is the only other option! Horlin doesn't apologise in mail and asks if the credit should go to the new order, AFTER my wife had asked for it to be done. She confirms. Horlin not in the next day, so the process is delayed. Yaseen Jacobs effects the credit. Zulpha Moyce confirms and says to use a PC as the app cannot handle debit cards. System cancels deal 1hr later, before she could get to a PC! Logging in now, the credit is gone! Am sure if she tries the purchase now the system will also tell her the discount code used has also been redeemed.