Useless service and incorrect billing

I took out a life insurance. I received every year for 4 years an anniversary letter, which they would advise me of what my payments would be for the next 12 months, To my surprise I discovered that of the 4 years I was paying 3 of the year s , Discovery was debiting more than the renewal letter. one year I was supposed to pay 11% more as per agreement, I discoverred they charged me 17% more. so three of the four years they where overcharging. I struggled for 2 months with the agent, Who is supposed to be one of there top agents, to get a direct answer from me, and had to push him to cancell when I requested a cancellation. I got numerous e-mails from Discovery to tell me that they will assist with the issue and cancellation. I advised them to call me, they callled and let the phone ring twice before they put down, I returned the call and the lady said she would get the agent that called me to contact me in 2 hours time , now over a week and still no call. My next step is to take it to the ombudsman