Max Bupa Health Insurance - illegal exclusion as pre existing decease

** Year back minor surgery took place which has no problem today.Also medical test shows no problem.But company underwritter doctor applied exclusion saying pre existing decease of dorsopathies in lumber region and waiting period of * years.As per irda rules pre existing decease means any surgery treatment medicine taken before ** manths of policy purchse.Now repeatedly asked to remove exclusionas it is against irda rules but they deny also not showing grounds.only say underwriting guidelines aproved by irda and are not accessable to public.Due to this unnecessary suffering for not proved decease and policy is pending.Worst suffering and loss to *lacs sum insured as i paid rs *****/-as premium but policy not received since * manth passed.Please help me to resolve issue.