service benefits after aquated in 420 case with benefit of doubts

My father was Mumbai municipal corporation employee and under suspension for 15 years due to fraud case under Ipc 420.He got aquated from this case after full trial with benefit of doubts remark in final order. During this period he got retired.Though he got aquated from the court Mumbai corporation his employer not giving service benefits of suspension period.What we can do in this regard please advise us.wheather we will get of benefits during suspension period or not what rule says about this