Reno OPPO 5 - repairs centre not exchanging for the same phone I had

I took a new contract with vodacom last month because I really wanted the Renno OPPO 5,the Galactic Silver one. The first phone overheated and was exchanged in the first month, 2 nd one also overheated and now it has been exchanged for the starry black colour. When I collected it, I told the guy that it's the wrong colour and he said it was the only colour they had. I'm not happy with this colour, I want the Galactic silver one. If I new this, I would have taken the Huawei Nova 8 phone from the beginning. It was difficult for me to choose between the two phones. Now I have to use a phone which colour I don't even like. Only my first installment went off. I'm so disappointed