can I get paid from my employer without my social security number?

I am an international student in US, just obtained my employment permit (aka OPT) in last month.Before I graduated from school, my boss orally promised to pay me full time after i graduated as a handbag designer. And it's been 2 month already, and he continues to pay me part time rate which is unjustify to comparing to my job load. I have sent in my application for SSN, but no answer yet. He said he can't pay me full time as I don't have SSN, but he already paid me over 10 times while I am still a student and worked for him as part timer. I felt he is taking advantage of this and making excuse to delay the full time paid to me. What can I do? Your advise is urgently needed and much appreciated. Thank you very much.