A receipt before they Fix the TV... Like WT****#

So Hisense requires proof of purchase for appliances that are still on Warranty. I am sitting with 2 Tv that broken, The screen is blank on both Tvs but the sound is there. One of the tvs is still under warranty bought it in 2018 but unfortunately I dont have the invoice anymore so I approach their customer care centre they tell me to provide proof of purchase how is that their concern.. Who keeps slips for 3 years.. Dont they have a system where that can use a Tv serial number to track the warranty date??????? . I am livid..