query for M type extension

HI...i'm a HK resident on employment Visa just Approved last month, due to my work i'm visiting Mainland very often and now my multiple entry M type is going to expire within a month time. i have tried to apply from hongkong but from there embassy need some kind of financial documents of supplier which i believe no one will provide. I got invitation letters from many companies also i got official letter from my company but still they need some kind of letter from govt. department about inviter .
also have asked Chinese exit entry bueauru in SZ but they said they can extend my stay but it might not for multiple entry. please advice what to do in this situation.