Belgrade airport which is capital of Serbia ,its v...

Belgrade airport which is capital of Serbia ,its very bad customer service ,all staff are very rude,they threaten .
I missed my flight and other 6 passenger with children ,i m coming from london to istanbul and got transit at Belgrate ,staff gave us wrong boarding pass, staff mamber spose to help us but they are defending her lady staff who gave us wrong boarding pass,she said sorry only ,they didn't give alternative flight , staff didn't not take responsibility and find salution for us.
I m at hotel to spend night and rebooked ticket with my own pocket.next day i talk station manager he said she is new lady .
They said we can't do nothing,police came ,asked all situation but he could not help us ,he took our passport and waste our time and disappeared, we found our passport from immigration office. please help me to find Airport authority who can i talk and i don't want next any body would suffer.
They should not treated like animal.