Fail to provide R1000 gift card on iphone 12 pre-order

I have received an email from istore on 11 December, it advised that pre-order iphone 12 from istore will receive an R1000 gift card. Thereafter I visited the Woodland istore on the same day and the manager advised that it is only applicable to order it online. I have order and fully paid online for a iphone 12 pro max, I have received the iphone in the morning of 18 December, but without the istore gift card as guided. I send an email to istore immediately, istore acknowledged the receipt but never responded on the email after 5 days. I am totally disappointed with such ********* business behaviours, I have lost confidence with istore and I would have bought it from takealot where they committed to providing a takealot voucher as well.