Hisense will not assist with TV

Purchase a Hisense TV at your own risk. *Baaaad* service! Technicians will not assist without a proof of purchase on my My Hisense 55 inch TV which is about 3 years old. After 3 years I do not have this. I am not asking for a repair, FREE OR OTHERWISE. Just asking for guidance or a firmware update. Apps have disappeared and Youtube is virtually unwatchable - thumbnail pictures have disappeared making navigation impossible. Never had such an indifferent response from service techs. Stay away.