Device Insurance (MTN & Pinnacle marketing)

I have a serious problem with MTN and Pinnacle Marketing. In October last year i reported a ****** cellphone device to insurance company working with MTN. The cellphone device was delivered this year around February and the amount i was billed was insurance inclusive. Till late this year i realized that my device was not insured hence was paying the very same amount of insurance inclusive. This never changed cause i changed my payment method to cash instead on debt order. So i called Pinnacle Marketing to get the IMEI number for the device that was delivered this year around February, they then registered the device as the new insurance policy and the double charged me for that month (R90 and R140). I have been trying to contact them via calls and email but MTN is continuing blocking my all outgoing calls due the the outstanding amount from the June invoice. Kindly assist as you previously helped me with the R5000 something outstanding from MTN due to ********** on my account.