Not paying of freelancing Work

I had made 17 illustrated banners for SNS System Indore for their NGO client and UNICEF which they distribute after making flex banners in villages of M.P., but they are not showing any intrest for paying me. The company had income lots with thats illustrated banners, but they dont want to share money with me. The company wants that, If I join the company as employer they pay me. I dont want to join the company because, the atmosphare and HR rules is not good in there.

I have all the original files, which I had made in flash and not give to the company, what can I do legally against company?