TFG ripping us off

In October 2017 I bought a Samsung J2 cellphone from Hi online and at beginning of march the cellphone out of the blue stopped working (screen blacked out) . I then took it back to one of foschini branches in Pretoria to be booked-in either for repairs or to be replaced since it was still under their six months return policy. The cellphone had no physical damage and has never been exposed to water. However now Foschini is telling me that I need to pay for the repairs (the amount exceeds the value of the cellphone) even though I strongly feel that cellphone came came with faults from the warehouse or factory (even when they took it for assessment it was confirmed that the phone didn't have physical damage nor was it exposed to water). I feel like their returns policy is nothing but a money making scheme.