Poor Service from Hisense

My Hisense smart tv stopped playing youtube ,netflix or Videos from a Usb. I took it in to the reatailer thet send it for repairs it came back 3 weeks later with the same problem. It was send back again for repairs Got it back again .The Technician told the retailer I must just check my connection there is nothing wrong with the TV. It Still has the same problem Hisense doesnt seem to want to help me Im very Unhappy with the service I am receiving.