If a product turns out to be defective, you may be entitled to a repair, replacement or refund (depending on whether the problem is major or cannot be fixed).
This applies regardless of whether the product is still under warranty.
Example only (outcome may differ in individual cases):
Danny buys a plasma TV for $6,000. It stops working after two years.
The store says they will not provide a repair or replacement as the TV only had a 12-month manufacturer’s warranty. They tell Danny he should have bought an extended warranty, which would have given five years’ cover.
However, it is reasonable for Danny to expect more than two years’ use from a $6,000 TV. He may be entitled to a repair, replacement or refund from the store.