It sounds like the seat has a broken cable/motor or linkage within the seat some investigation will need to be done to see what needs to be replaced. Kia as a car manufacturer put a lot of great technical information and work shop manuals on line for free for Kia owners. www.kiatechinfo.com
It takes approx 2-3 minutes to unscrew the plastic around the seat and another minute or so to unplug the old switch and pop in a new switch. If you can purchase the switch yourself (approx. $150-200) you can do this yourself. You literally unplug the old seat switch and plug in the new one.
To test whether it is really the seat switch that's faulty, remove the seat switch from the working power seat (ie: if the driver's side seat is faulty, remove the passenger side seat switch). Plug this into the driver side seat switch plug. Then attempt to maneuver the seat. If this works, you know that replacement of the faulty switch will fix your proplem. If it doesn't work, then you have a problem with some other component of the seat mechanism and will need to further research to figure out what is wrong.