When you apply for a Chinese visa, you will have to pay a fixed administration fee to the Chinese embassy. Be extremely cautious if someone tells you that they can get you a visa via underground means and demands a large sum of money from you. Note the following:

The Chinese embassy approves student visas in strict accordance with the relevant regulations and on the basis of the application credentials of each visa applicant, including whether or not you are a real student, and whether or not your application materials are complete and accurate. If the visa requirements are not satisfied, it is impossible to obtain a visa via underground means.

In other words, your visa application will only be approved providing you come to China for study purposes and not harboring intentions of working or staying illegally, and providing your application materials are complete and submitted in sufficient time.

You must hold the correct visa to enter China. Only students from North America, South America, Europe, East Asia and South East Asia can change their visa type after entering China. Under normal circumstances, it is very difficult for students from other regions to change their visa, for example to change an L visa to a student (X) visa.