insurance do not want to pay OUT

I have change my banking details i gave MTN my new banking details to debit from , now when i was clamimng my phone last week i was told to call my insurance that i joined at mtn , i called callsure insurance they told me the account was closed in October becouse my initial bank account was clossed and they never called me and tell me that my account is not paid and im under impression it is MTN Insurance when i give them the new details they are suppose to pass it to their insurance , now they are not paying my new cellphone and i got Armed ******* last week , what must i do at this moment , they never told me about the different company . i even offered to pay the insurance the installments owed from October but they refused they told me there's nothing they can do .