Worst ONLINE shopping experience ever !!

Worst ONLINE shopping experience ever !! On the 9th April, I bought shoes for my son at a cost R618.00. After numerous phone calls and emails, woolworths failed to delivery my parcel even although the consultants confirmed on redelivery escalation they still failed to delivery. Eventually on the 7th May which is almost a month later, I spoke to another consultant whom I requested a refund. Because my online purchase was via payflex I was told refund would be in a form of a voucher to purchase at a woolies store nearby. FINE ...24hours later I recieve the voucher SMS, but tell me why is this refund Voucher R600.00 ??? INSTEAD OF THE ORDER AMOUNT OF R618.00, what happened to the R18.00 ???, NOW I need to send another email and ask about the shortfall ??? I'm sooo shook and disappointed at the service