Shesha month to month home internet data bill

I am on the month to month data plan with MTN for shesha home internet. MTN has been charging extra R20 for sending me monthly statement on my for the passed 8 months. I did not sign-up to receive the statement as I can easily track my data on the app, I have been calling them each month to cancel those extra R20 for statement, they always promise that it has been cancelled but my bill always comes back with that R20 for statement. Meaning they are not cancelling it on their side, they are lying to me.