MINI AND FRENCH CITI refusal to refund

I went to MINI AND FRENCH CITI on the 04-05-2019. I advised the sales person that I need the Mini Cooper Convertible R52 from wheel arch cover. He came back with the cover and I paid for Item cash (R350), immediately after paying and getting the part I went to check if the part fitted And it turned out that they sold me the incorrect part I immediately went back to the store to ask For a refund and I was sent to the manager who came out with a gun on his waist and advised They have a no refund policy, they will credit the amount and courier (for free) the part on Tuesday which Will be on the 7th of May 2019. They also said they will call me on that Monday to provide me with An update. Days passed without any feedback from them, so I called back 9th of May 2019 and I was told the product was going to be delivered on the 10th of May 2019. Days passed I called in On the 13th asking for a refund as they had failed to deliver on their promise I was advised that the Part is on its way to my listed address. Days later I call in again 16 of May 2016 and I ask for a Refund they refuse to assist and say that the part is already on its way and they cannot refund. I asked for a tracking number as proof that the have couriered and they refused to do so.