What’s wrong with this university? why are they so lazy !

I uploaded my i20 documents more than 20 days ago called them then the international admissions office guys said documents are right you will get the I20 soon. In the mail it says 10 days because of late I20 I had to defer my admissions from spring to fall now again same case. I have been calling them but no one pick up the call, mailed the admission office no reply. What to do now?