I need help.

Hello my name is Mike, I have X2 visa now in China which I got from a school here and I want to come back in two weeks time and I can't go back to PRC with it because it has no entry so I will need to get an entry permit in Ghana to go back to PRC. i have an information that embassy don't give entry permit again to any person that have extended his or her entry permit in PRC unless you bring a latter from PRC telling them why you do the extension over there, now my question is this, where will this letter come from? From immigration, School, or company. Please I need an answer so that I will know what type of letter to bring. Thanks