Is there a possibility that i can convert my tourist visa to working visa?

In China, private companies can employ foreigners but they should go through certain procedure. To change your current L visa to Z visa within China is possible but you have to find yourself a powerful visa agency. I was told that they charge very high for their service and some requires applicants to get it in HK. So, may I know your nationality that I may help if you can apply in HK by yourself.