legal question with head-hunter, agony uncle pls help!

I just found out this page, its really nice to have agony uncle in this forum to provide insights for our social encounters.

I am currently having some problems with my head-hunter. The whole story is I found a very nice job opening from web and approached R agent to present me to S company because S HR department only deals with head-hunters. I passed the interview and a day later the offer was confirmed by S. Things really get ugly when I received offer letter and contracts from R. I did not sign contracts with R because I am not happy with some terms, though R agent pushed me a few times. However, on the other side, R asked S to pay some amount which is beyond the regular contracts S signed with other agents. In such case, R did not get any agreements from both sides. Then R sent a email to me stating that though I can change agents to contact S again on this job, but R has the right to place legal actions with S, which means my opportunity to S was totally blocked out by R because R submitted my applications to S first.

Does R has the right to do so? What should I do to turnover the situation in favor of me to get the job in S? Pls do help me, agony uncle chung.