Shocking after sales service - Hisense

Started off brilliant - my son's faulty TV was collected by Hisense and taken for inspection. Within a few days I was told that the TV cannot be repaired and must be replaced. TV was returned along with the report and that was when the horror started. I have been trying for days to get a comment out of Hisense regarding the replacement. No-one responds to email or complaints lodged on their website? It is very apparent that Hisense use their extended warranty and guarantee on their products to get customers to buy their product but when it comes to honoring those guarantees you cannot get service or assistance