Debit Order with no contract in place

Good morning, in May MTN started debiting my bank account. All these transactions I manually reversed via my banking app.

The problem is that I don't have a MTN contract, nothing signed or no contract taken out with MTN.

I want to follow up wrt the situation as I want to know if anything is "attached" to my name using an ******** method like **** etc as my bank account was jeopardized.

Are you able to supply me with more info or how do I go about finding out what the situation is with the D/O that was going off (which I reversed every time).

regards, Monique ***