Misleading Warranty and Sales Transaction

Purchased a Panasonic 55 inch TV from Sounds Great in Centurion. Had it for 15 months and it became faulty. It comes with a four year warranty. The repairer Pan Solutions determined that they cant repair the TV and advised Sounds Great Centurion to credit me. Sounds Great Centurion now claim that the product has depreciated and they can only replace it with a cheap brand TV. So what is the use of the 4 year Panasonic Warranty.