Secondary school leaving certificate nostrification in Czech Republic [closed]

I am a Ukrainian citizen. I have applied for a bachelor's degree program at the University of South Bohemia (Ceske Budejovice, Czech Republic), and they have accepted my application on the condition that I will get my secondary school leaving certificate (the certificate is issued by a Russian school, and has the apostille on it) nostrificated (recognized/certified as equivalent) by the interview/exams date, which is the 18th of June.

So now I'm in trouble. From multiple sources I have figured out that I need to submit documents for nostrification personally. To do that I need to go to the Czech Republic. For that I need a short term visa. The problem is that the university can't make me an invitation for the visa to handle nostrification, they can only invite me to exams.

I tried to find some Czech agencies to assist such situations, but they seem to be slowpokes, and do not respond to emails. The nostrification procedure takes 30-60 days, so I must hurry up, or I'll be screwed. All I have right now (aside from a ton of papers, that should confirm my certificate) to present to visa issuing authorities is a letter from the university that states I need to go through nostrification procedure, a bunch of email correspondence with University and a government official from Prague, who confirmed, that I have to present all the papers personally.

So, what should I do? How do I get a short term visa to submit my nostrification documents and to take the nostrification exams 30-60 days afterwards? Finances are not a problem in my case.