Extremely rude Airport staff and no explanation for their actions

A relative has been visiting Turkey many times but recently (he's got EU passport) got refused entry and now being returned.

The explanation on the form (they gave him) says entry ban and with a lot of push, the only answer they provided is that it seems his name (common name) matches with some other profile aka case of mistaken ID.

The staff is extremely rude and doesn't care to respond as he can't speak Turkish and this has never happened to him.

Anyone knows someone local who can help or bother explaining him something because he's got no clue why there's an issue this time.