Help with non-English characters

I have just installed VBseo, and I see that I have a problem with non-English characters in the urls.

In my settings, the option "Replace Non-English Characters in URLs?" is set to yes.

It does replace some of the characters (turns đ to d, ž to z and š to s), but there is a problem with č and ć. It omits them completely!

It means that instead of the keyword in the url, I get only a half of word. For example, instead of

...čišćenje-tijela.hml i get ...nje-tijela.html

Please tell me how I can fix it.

Please check : vBSEO.com Helpdesk

Thanks a lot!