MTN insurance rejected claim because of teller error

In March I switched banks and then went to MTN Wonderpark Mall in Pretoria to let them know of the changes. The person who assisted me only switched the debit order for the Cellphone contract and left the Cellphone insurance. As a result of that the Cellphone insurance lapsed. When my phone was ****** I tried to claim and that is only when they send me an SMS claiming my insurance was cancelled because had not paid the month before. I never received any communication from MTN insurance regarding missed payment or the intentions to cancel my insurance.

I only received the one SMS alerting me that my insurance was cancelled on the day of the claim. I was honest with MTN, they debited me for months and now I'm told stories. Please help me