Struggling with repair of brand new bicycle

I bought my son a brand new bicycle on 21.08.2022 from Game Greenacres store in Port Elizabeth. On 26.08.2022 the bicycles back wheel and brake system gives problems after riding on it for the first time. Because we not from P.E we had to hire a courier vehicle wich cost us R650 to take the bicycle to game and it was R650 to bring it back. After two weeks the bicycle came back and we were told that it was fixed. On 4.Dec 2022 my son ride on the bicycle for the first time after it came back from Game and it is giving the same problem. I phone Game on the 5.12.2022 and was told We had to bring the bicycle back on our own expense with money that I don't have. Since it was a brand new bicycle my son doesn't have any enjoyment of this bike. I struggle to get hold of the manager of that department. It is really a struggle, but will take the legal route now.