Bad Customer Service

I bought Sinotec tv at game on 7TH April 2020 with the guarantee of 5yrs, then I accidentally lost the proof of purchase then I went to game Vaal Mall for enquiry they said proof of purchase is needed to book it in, I engaged their head office customer service and they took the matter back to game Vaal Mall for their assistance but they said the tv is no longer part of their stock so won't be able to assist me .