I have identified that Insurance Bundle MTNAR954511S (contract date: 07-03-2024 to 30-12-9999) has been erroneously added to my invoice

I have identified that Insurance Bundle MTNAR954511S (contract date: 07-03-2024 to 30-12-9999) has been erroneously added to my invoice. This insurance policy does not belong to me. I should only have 3 active insurance policies, but I am currently being billed for 4. I called MTN insurance on the 29th July and they confirmed that the 4th insurance belongs to someone else. They have cancelled that insurance. however on the 12th of August when my new bill was generated the same incorrect insurance charge was added again. They are supposed to refund me for all the months they have billed me for this insurance but they have not gotten back to me regarding my refund.