Not getting reliving letter from previous emoloyer

My organisation i am joining i needed relieving letter copy from ABC Bank, to which i sent mail to ABC Bank requesting for same. However the HR replied me back that they had terminated me that too without informing me for non serving full notice period which was told tom me after 3 years after leaving the bank and as far as i understand termination is done when an employees candidature is found guilty or any forgery is done during employment period on the contrary i was one of the best performing employee in my Zone because of which i got many awards and recognition's during my employment tenure. Also, my next employer was ready to buy my full notice period of 3 months of ABC Bank to which the Bank denied and i served 1.5 months notice with Indusind bank as my next employer wanted me to join on priority to which ABC Bank has made me a victim of same by terminating me without any notice or intimation for non serving full 3 months notice which was a big shock to me as i came to know about same after 3 years. Would request your kind and urgent help in availing my relieving letter from ABC Bank as feel free to contact me.