Serbia visa

So I'm a Kenyan citizen and my fiancé is Serbian with Serbian passport but born and lives in Germany. We wanted to visit Serbia this xmas and also make arrangements for our wedding because we would like to do it in Serbia. Only problem is I need an invitation letter, she took the letter to the Serbian embassy in Germany and they said it can't be done there it can only strictly be done by somebody living in Serbia. So what can we do now?
Unluckily her whole family is in Germany so nobody that could get it done for us

If you have a schenyeng or American visa you may enter with same.

My resident permit was not extended so I don't have a schengen visa anymore. We want to get married so I can also get my resident permit back and we wanted to do it in Serbia because its easier there

Your fiancee could get one of his relatives here to go to the department of police who handles these immigration matters and his relative could be your gurantor, meaning, his relative could fill out the forms as the person inviting you. Otherwise your fiancee will need to come here before you and go through the normal procedures himself.