GaurdRisk Insurance MTN never again.

I took out a cellphone contract with MTN 2018 and at the time also took out an insurance underwritten by GaurdRisk.i finished paying off the cellphone contract and the insurance continued. I cancelled the insurance in the next month post end of the cellphone contract however they kept billing me even after the cancellation date. I then followed up with MTN an I was told it was the insurance that was billing me still. And now they say there is an outstanding balance that owe which doesn't make sense at all because I cancelled everything and never missed a month. When I followed up with gaurdrisk they said the error was on their side but I am still getting calls that I am owing money. I have tried everything to clear my name even now after 1year 6month. So frustrating too much , doesn't make sense how that money could be accumating when it is insurance (you pay we cover you ,no pay no cover).