Legality of Departmental Disciplinary Action

Greetings to all the esteemed lawyers on this site. I am a Government Servant from the state of Tamil Nadu. Recently I had been on leave on loss of pay for a period of 10 months to facilitate preparation for a competitive examination. Initially I had applied and obtained the permission of the Competent Authority for leave on loss of pay for a period of 3 months. Thereafter, I had send appropriate requests for extension of leave on loss of pay through post and all my requests for extension of leave on loss of pay had been accepted by the leave sanctioning authority. In this regard, I rejoined duty recently after being on leave on loss of pay for a period of 10 months with appropriate permission from the authorities. Two months after I had rejoined duty, I have now been informed that my Department is considering the initiation of Departmental Disciplinary action against me for being on Leave on loss of pay for more than 6 months at a time. As per my service rules, departmental action could be initiated if an employee is on leave continuously for more than 6 months. However, in my case, the authorities did not decline my requisition letters for leave extension beyond 6 months. They accepted all my leave extension letters. Moreover, I had mentioned in my leave extension request letters that If the department instructs me to join duty, then I am readily available to resume duties at any time. But the authorities never cared to inform me to join duty to avoid Disciplinary action. I feel that the authorities had the opportunity to decline my leave letter seeking extension beyond 6 months, but they choose not to and instead accepted all my leave letters. Based on the prior permission granted by the authorities for my entire leave on loss of pay period of 10 months, I feel that the initiation of Departmental action is untenable against the ethics of natural justice. I wish to hear from the legal experts on the legality of the issue; whether a departmental disciplinary action under these circumstances would be legally permissible by law. Any case laws in this regard as citations would be of immense help. Thank you.