To keep the valuable 7 year warranty on a Kia intact any maintenance should be carried out either by a Kia garage or a VAT registered garage who will use genuine Kia parts.

DIY will result in loosing the warranty on at least the part of the car worked on should there, in this case, be an engine related issue resulting from the filter change.

For the sake of the warranty get your Kia dealer to change it. You might save a few pounds but end up loosing hundreds plus reducing the value of the car in the process.