Central govt resignation

I am a central government class b employee. In Jan 16 I took a leave with headquarter leaving permission to give upsc exam. But later I had to travel home due to my mother's bad health. Since my mother has been un well and suffers from arthritis et al I could not resume duty but intimated them through speed post twice. In April I decided to tender resignation as I had to be with my mom during her Illness. When I arrived at office I was given a memorandum demanding an explanation for my absence and I was told that a file for disciplinary action against me for unauthorised leave has been opened with the vigilance dept. Sir I have submitted my resignation to the dept and requested for not furthering any displinary action against me as I have submitted medical of my mother and requested them to relieve me at the earliest taking a sympathetic view of my case. But I feel sorry to say that instead I m being harassed and being told that it will take time and we can't work according to you. I feel depressed and helpless. I am afraid if they chargesheet me I won't be able to later pursue my upsc dream