Bad service

I bought a tv 4 years ago that is on warranty with sinotec my tv stopped working in June the tv will go off on its own and not come on sinotec fetched it for repairs and delivered the tv the same problem happen again in October they sent there couriers to fetch the tv for repairs i contacted them at the middle of oct they informed the tv is repaired and ready for delivery up till today i have not received my 55 inch tv they service center called fast care service centre infoms me they cannot find my tv i have been sending them emails i have been calling them with no satisfaction they say to me that they delivered the tv in june i informed them it was booked for a second time I have even sent them proof of collection which they requested that the tv was sent back for repairs there customer service is so bad how can you lose a 55 inch tv I am getting no way with these guys no one seems to know whats happening Im in durban and they are based in jhb i just dont know what to do