Is the key fob on my Kia Rio covered by warranty?

We have owned three Kias, a Sportage, Rio and a recently purchased Cerato, all of which have performed well.  But last week my wife’s Rio, which is still under warranty, caused me to ponder our satisfaction level with Kia. On returning from shopping, in our driveway, whilst folding the ignition key into the module, it fell apart. Fortunately this occurred at home and whilst stationery. To my astonishment the local Kia agent quoted me approximately $600 to replace the key. It would also seem that Kia is reluctant to accept a warranty claim for this.  I wondered what your view might be about this and the high cost of a replacement key.