Regularisation of job from contract

Sir I am working in an Autonomous body of Govt. of India. My query is about my job. In fact there are numerous such cases in our organization facing the same situation all over india. 1. I joined the Organization on short term contract basis in 1999, as office kept me on need basis without advertising in news papers. 2. The contact was renewed and renewed for years based on my performance. 3. In Year 2005 my contract period was extended to 3 years after facing a review committee, again without any advertisement in news paper. 4. In Year 2005 my contract period was extended to 5 years after facing a review committee, again without any advertisement in news paper. 5. In year 2007, I was regularized with instructions from my Head Quarters New Delhi after facing the review committee. Some guy has challenged my appointment saying that I was over age when regularized and there was no advertisement in news papers for the posts. Sir, now my head quarter is suspecting our (almost 150 cases all over india) appointment and threatening to terminate our appointment. My question is that 1. Can HQ terminate me and what should be the course of action if HQ does so. 2. what is the way out.