Maternity Benefits Partially Denied by Public School

This is regarding my wife, she has taken maternity leave initially from December to February and extended to June from her school where she was employed for last 2.5 years. As per school’s rules, the maternity benefit is of 3 months leave out of which only 1 month is paid and rest is unpaid. The school has paid only 1 month salary in by wife’s bank account. Now my wife has resigned and left the job. Can we claim the remaining 2 months’ salary as maternity benefit from the school under Maternity Benefit Act 1961? Notable Point: The school has huge dictatorial style with no written and agreed policies, all work under whims of the principal. My wife was given just the offer letter and no appointment letter. In offer letter it was written that you are joining upon the mutually agreed terms and conditions. There are huge financial irregularities of other staff salary as well. My wife had given a written application before going for maternity leave. What is the best possible legal way to claim the amount ?