I'm from Lebanon, I want to stay in China for about 2 months, but I get a visa with 30 days stay duration, how can I do?

hi we are mohammad bannout and malik el tawil from lebanon , we are right now in China (Xian) , we have reached china on June 29 . we will stay in china about 2 months , but we have noticed yesterday that it's registered on our visas just 30 days in the case of duration of stay ,so the chinese embassy made a mistake in the case of duration of stay, it must be 2 months . even though that the chinese embassy knows from the application form ,the invitation to china and the booking of our tickets that we will stay in china for 2 months and we have paid for this duration .I'm trying to call the chinese embassy in lebanon but no one answers!!what we are supposed to do now??? please we have to fix this problem as soon as possible... thank you