Threat of warranty cancellation

I have a KIA K2700 which was purchased and exclusively maintained with KIA Klerksdorp. In 2014 on about 80 000km the vehicle had a problem which was sorted out with KIA klerksdorp under warranty without any questions asked. Now in 2015 on about 85000km I have a problem that seemed to be a injector. My vehicle has a full service history with KIA. When it was taken in to KIA in Mafikeng which is where the vehicle is working currently. The workshop manager or manager. Told my foreman that the vehicle was definitely not maintained with KIA, because of certain procedural KIA workshop practices that were apparently not followed by KIA in klerksdorp. This allegation was made by KIA in mafikeng. Now I spoke to KIA in klerksdorp but I want to know. How is this possible. How can this happen where someone can analyze where a vehicle was maintained despite a full service history. And make allegations based on that. I am very unhappy it is the first time that I have had such a bad experience with KIA. This is not the first, the last or the only Kia product that I own. I am very unhappy. Vehicle details : HWM048NW, Vin : KNCSHX71LD***, ENGINE : J***