Worst Customer service i have experienced in my life , TV still not working correctly

Good Day, i bought a Hisense 55" LED tv from Hisense in 2017 , about +- 1 year after i bought the TV it started giving problems where it would randomly go black but the sound would still play but with nothing on the screen , then with much trouble i logged a complaint with hisesnse then they replaced the mother board of the tv . Tv ran fine for +- 1 Year then it started to do the same thing, i then contact hisense again and they came out to replace the motherboard for the 2nd time . The TV then ran fine for +- 1-2 weeks and had the exact same problem, i logged it with hisense again and they took the tv into the repair center and tested it for 1 week then told me there is nothing wrong with the product. Now i am fighting with them as the tv can’t have the same problem 3 times in a row. Tried to call them 100 times and this is not an joke, check there call logs and see . No one is getting back to me and i have sent them video evidence of the tv doing the same thing and they are just ignoring me

Logged with service centre more than 3 times Emailed ***nor and Ruben and complaints department, never got a call back Tried more than 20 times to call them today, you can check there call logs they just put down the phone I really dont know what to do anymore