No response to warranty query

I have had my Kia Rio for 5 years now and a year before the warranty expired the key broke. The service adviser at the time was Casper( who has now left) promised that it would be replaced under warranty. After several attempts for an answer it was always he is waiting for Kia South Africa. After a year and 2 days before the warranty expired I went to Kia and spoke to another adviser at the Silverlakes branch, who said she would ask Kia South Africa again. I have followed up at least 15 times with still now response. I love the car, but if this is how they treat customers, I will never buy another one.