Received the wrong item three times!

On Sunday 29th of August I placed an order for shoes on Takealot. I ordered a UK 11 and when it arrived on Monday the 30th of August, I received a UK 10. I arranged for an exchange and they delivered the wrong size again. Naturally I arrange for another exchange where the call center agent promises me that the warehouse staff will ensure that the correct size will be sent. The third pair of shoes arrived today and once again it's the wrong size. Clearly it's a bunch of illiterate idiots working in the warehouse because they can't distinguish the difference between US and UK sizes. They are ignoring my emails and not returning my calls at this point and I am fed up. Takealot has made R39500 from me so far this year but they will definitely not see amother cent. Their service is pathetic and I'm lost for words. I don't know what else to do because it seems that I'm going to receive the wrong size every time. Making a mistake once is understandable but three times? It feels like a practical joke because i can not believe that a company employs such a useless bunch of people. Just send me what I ordered!