how does an uplift number work for a TV

hi have a faulty hisense 75m7900 hisense wont fix i guess due to cost of a new panel , retailer is ao.com hisense said i will have the uplift code in the next 2 days , but how does it work do i pick a tv to the same value as paid for the current one ? what happens if i pick a tv that is less in value anyone know thanks . do you get refunded the differance