Billing issues

Hi I would like to express my frustration regarding the billing issue that occurred on my account. Last month I was debited fine then all of sudden this month the debit order was triple the amount, when I called customer I was told that it was the money for two devices and I upgraded from my previous phone. I was also told that the agent who helped me didn’t cancel the insurance and now I was billed for two devices insurance while the agent who helped me at the store told me he did cancel everything. Now I need to call the insurance company to cancel while they’re the ones who made the insurance for me 😡🤬.. please assist or I will reverse the debit order.