Poor service from Hisense and refusal to honour warranty

I bought a 50" Hisense TV from Pick n Pay Hyper in Farie Glenn Pretoria. After 1 and half years the TV began to stop showing pictures. The screen just goes black while watching. I have been sent from pilar to post by *********** and rude Hisense employees. I requested an exchange or refund but I am told they do not offer that they only repair, yet they have repaired and replaced LED backlights on 4 separate occasions already! I regret ever purchasing a Hisense TV! Their product simply doesn't last and they will not honour their own warranty!