Overcharging on Insurance on Cell Contract

I have been overcharged on my vodacom insurance on a contract since November 2021. I have been phoning and emailing monthly to get it sorted. They are still billing me for two policies and I am getting no results in getting this sorted. When I get through on the phone the consultant cannot put me through to the department that sorts it and only logs emails and phone calls. They can track all the correspondence but nothing is done about it.