Wrong caste certificate issued by tahashildar

Sir my friend Prakash Sarapure got appointed on 13/12/2006 as Assistant Engineer(El) at KPTCL Karnataka under categary 2A ( Caste Hindu Hanabar) ( As per the certificate issued by Tahashildar) . Board asked Sindhutwa Pramana patra for declaration of probationary period . But DC , Backward classes and Minorities welfare department issued a letter saying the Hindu Hanabar caste comes under category one not under 2A it comes under category 1. As per that letter the department enquiry conducted on by friend for giving false caste certificate , but it was the mistake of tahashildar who issued the caste certificate by counting Hindu Hanabar in 2A ( Tahashildar has given letter for that accepting its mistake made by his office) as it was mistake from tahashildar my friend was acquitted from charges of submitting false caste certificate and got cleared of charges framed on him. But now problem is to declare probationary period under which category his appointment should be considered . 2A he cant claim, category 1 already post filled as per vacancy. General category also filled. Pls guide us in this matter