Technical Resignation and Prorata Pension

Dear Sir, I served Water Resources Department, Government of Bihar from 02.07.1987 to 20.06.2004. My application for the Post of Reader in the Department of Civil Engineering, Institute of Technology, Banaras Hindu University Varanasi was forwarded through proper channel. On selection, I joined the post on 21.06.2004 after taking 3 years lien from WRD, Govt. of Bihar. After one year, on 21.06.2005. BHU conformed my service and I continued here. I have been requesting to BHU to open my GPF account. But, BHU asks for prorata pension from Govt of Bihar, saying that BHU is Centrally Autonomous Body (CAB). I tendered Technical Resignation from WRD, Govt. of Bihar on 17.03.2011, but Govt. of Bihar accepted it on 19.09.2011 as "Resignation". My past services from 02.07.1987 to 20.06.2004 is not being considered by BHU for want of prorata pension amount and Bihar Government does not want to give this, saying that (i) the selection is based on personal application, and (ii) the pension has to be given by the the employer from where the employee retires after completing the service. BHU is counting my service only from 20.06.2004, although I have been consistently putting that I am coming from earlier service under GPF scheme and pensionable service. My question is : who is at fault, WRD, Govt. of Bihar by not admitting and paying prorata pension to BHU, despite having forwarded the application, granting the 3 years lien and sending LPC to BHU and being fully aware that BHU is Central Autonomous Body (CAB) (not Central Government Department) and prorata pension needs to be paid to such bodies? OR BHU, who confirmed my service with all facts on records, without asking any liability from WRD, Govt. of Bihar and now denying my entry into Old Pension Scheme for want of Prorata pensionary amount from WRD (which anyway does not seem to accept and agree to may any money towards that? What are the options for me ?