IT company policy issue

Dear Sir, Iam a female employee at L & T Infotech Mumbai with 8 years of exp. I joined the company 1.5 years ago. And as I am technically exceptionally capable I am assigned lead role to handle teams though as per my designation I m not a lead. After the annual appraisals I got higher rating for my best performance in team and also have received client appreciations. But in the annual appraisal cycle I was not promoted to lead despite my high calibre and 8 years of exp. My manager said there is a comp any policy that one must complete two years to get promoted. I could accept this policy of it is documented anywhere and available to employees. I spoke with company HR also and he said the company policy exists as a secret corporate guidelines and it cannot be shared with employees in a handbook but only managers know about it. My question is how can a policy related to individual growth be a secret. Please suggest am I in capacity to issue legal notice to company and managers for such unfair trade practices. I being female denied promotion despite best performance proves that it is not an equal opportunity employer and discriminate on gender. And now I have decided to resign and in notice period can this be termed as conducive discharge. There are no negotiations from my managers side. Appreciate your response let me know my rights as power labor law.