asking for helped for my cancelled z visa by an immmigration police in shenzhen without my notice

i am a cameroonian in china my viza has just being councelled now without my notice and i have being given an exit viza to leave now i have no means and i have a valid viza i just sent my case to the embassy please help me and other cameroonian here i dont know where to go to this is a friday evening i called them and it was closed immediately after receiving my passport so how can i exit un noticed like this i need some answers on this please help me