I did same they ask 2nd time police certificate I m in CanadaWrite a letter of explanation about the situation of northern Cyprus. They already know what is going on but they are not the one to justify it . You must justify your case . If they refuse the police certificate from North Cyprus they should refuse the diploma as well. But as far as I know WES or other organisation in northern America accept northern Cyprus diploma. So just write a good letter of explanation, including map and add your police certificate from Northern Cyprus. That's all you can do. Keep your fingers crossed and let the gods decide your faith