Unauthorised payment

I made a payment via the MTN App money went out from my bank account and I got notification from my bank and their system that they have received my payment this was done on the 25/02/2021. To my surprise today 03/03/2021 money went out again from my account. When I contact them they just brushing me off and refusing to refund me! They have certainly lost me as a customer I’m cancelling my contracts with them.