Lip-Synch issue on 55\ Smart TV"

Hi<br> I bought a Hisense 55\ Smart TV from Makro. Since the first day of using it I have Lip-Sync issue on the unit. I logged a call with Hisense and they send out a technician to come and test the unit. The technician said that he had to upgrade the software. A few days later he came back and replace the motherboard. After replacing the motherboard I still had the Lip-Sync issues. They just closed the call and never sorted the issue. I logged a call again more than a week ago and still did not receive any feedback as to what they are going to do to resolve the issue. This is ridiculous and I need this resolved asap. From the 1st day I bought the TV I could not use the Youtube app. After replacing the Motherboard the response on the TV is so slow that I can't even use youtube through the browser on the TV. My brother in Law has the exact same TV and the TV is doing exactly the same Lip-sync