2 Unauthorized Debit Orders this month already, Months After I Closed my Account

On the first of this month and again this morning I noticed that I had unauthorized Debit Orders on my bank account, from Telkom. On the second of Feb 2018, I queried it with Telkom (Case: ********** 1 / ********** 0) and the only feedback I received from them (yesterday) is that the query is with the billing department. They don't want to give me contact / email details for the billing department, and can't give me feedback as to when I can expect feedback.