Unauthorized deduction

I am very unhappy with the way queries are handled. My statement depicts my fixed monthly amount due, but on the app it is 3 X the amount. According to Vodacom they have a different statement dated 11th August 2020 also for 3 times the amount. After a battle, it is established that it's due to a "cash reverse". ***? My account is paid via debit order every month, plus this is one of my security questions. Now.....cash reversed. How do you do that? Now they want my bank statements to show that I paid via debit order. If it didn't go through, the account would be blocked by now. How can the company not see for itself that it's paid with debit order? Till now I hàve not even received anything showing anything about this alleged amount. If I didn't see this on my app... My opinion: Vodacom is not authorized to deduct more from my account than the statement of account and invoices dated 3 August 2020!

P.S. How do you supposedly make a cash reversal if you pay via debit order?