Utterly Disgusted by Hisense

I bought a 50" Smart TV from Makro 31/08/2017. After 1 year my TV would not function when I use my USB port my TV would just switch on and off by itself. A technician came to replace my USB port and upgraded the TV. My TV is giving me the same problem but this time I can't use the USB port, the screen mirroring functionality and my AV port. I'm totally disappointed with quality of my Smart TV after I spent a fortune on it. Today I sent an email to service@hisense and a lady called Veronica emailed me back expressing no ampathy at all regarding my query, instead she blatantly told me I have my device for longer than six months and that I am not eligible for an exchange. She didn't even assure me that a technician has been assigned to my case. That was totally rude of her and my question is, will a technician constantly repair my TV? What happens when the 4 year warranty runs out? I am extremely disappointed with the quality of Hisense as well as their service!