Promised refund not materialising for goods that Makro cannot fulfill

I ordered 48 mm x 100 m (box of 36 rolls) packaging tape for our business. After the order was placed online, the supplier phoned me. He indicated they do not have 100 m rolls in stock. They only have 50 m rolls, and could supply 72 rolls instead (and it would be over a month before the 100 m rolls became available). I phoned him back, asking him to cancel, as the 50 m rolls do not suit our purposes, and I need the 100 m rolls now. He indicated I needed to contact Makro for a cancellation. (Makro’s processes should not even have allowed the order to proceed if there was no stock.) I phoned “order cancellations” at Makro before even 1 hour of placing the order was up. The gentleman told me he had no authority to cancel the order. (So I would ask what is the point of having a number for cancellations where someone does not actually have the authority to do what is advertised?) The sales and marketing team would be in touch, he said. Nobody phoned me several days later. So I phoned and was placed on hold. I gave up and emailed. I received a support ticket saying that the finance department would be in touch, and the support ticket has been attended to. I got an email from finance saying the support ticket has been attended to. This is shocking service. Bear in mind – I’m not cancelling on a whim. Makro cannot actually fulfill the order for which money was accepted in the time frame they committed to.

I want my R800 back. Makro has taken money for a product advertised that was not actually available. Rightfully, I am entitiled to my money back. Please tell me how I am supposed to get my money back from Makro? I have now ordered from another supplier (on Takealot!) who can actually deliver what was advertised in a reasonable time frame.

What is the process for getting my money back please?