Lost parts during repair - Consumer Complaint for KIA MOTORS - HEAD OFFICE (Complaints)

I took my car to Kia Polokwane. The repair quotation was 250000 which I couldn’t afford . I had to take my car now when We try to fix the car we found extra part of another car which is not for my car. And shortage of 1 part tensioner bracket. When I call the dealer they say there is nothing they can do . It’s like they are not taking the responsibility for their own mistake. They say there is no way that they could have misplaced my car part because they always put every part in the car. As much as they put extra part in my car they could have put my part in another persons car. Please help with this regards .