Need help in extending L visa in Shenzhen

I am an American citizen currently living in Shenzhen. I have been in China now since 2008 on an L visa.
In the past I have had no problems in obtaining another L visa by going to Hong Kong and using an agency.
I have done this 9 times. On my 10th try at obtaining another 6 month, M entry, 30 day stay, I had no luck.
I was only given a 1 Entry and a 10 day L visa. I really want to stay in China for a few more years if I can.
Has anyone else ever been in this situation and if so how did you handle it? Time is running out for me.