Question for KIA MOTORS - HEAD OFFICE (Complaints)

A very concerned customer. I own an Optima, a Picanto as well as a Hyundai H100 - which then makes me say I am a loyal KIA customer. In November 2014 while my Optima was still under warrantee, the driver's side window mechanism became disfunctional. I took the car in at KIA Edenvale Meadowdale. Since then I have always bees told the part has not arrive since it was ordered. I have been in such a situation for the full 6 months - do I call this a service? Lately no one wants to even talk to me when I call, I leave my number to be called back and nobody does. What should I do now? My car reg number is CB25JTGP