You can write to Ombudsman for grievance redressal if you have been subject to unfair increases in premium not permissible as per IRDA guidelines. Insurers can only charge premium as filed and approved by the IRDA. The suggested course of action is as follows:

1. Write to the grievance officer of the insurer stating your grievance and asking reasons as to why your premiums have been increased and the relevant IRDA approved rate chart for the same.
2. If there is no response within 30 days, you can file a grievance with the ombudsman. A simple plain paper complaint would do. No need for any legal support. You should get a decision within 3 months.