Unauthorized deductions!!

I do not have an account with MTN but monies, which I later reversed, have been debited from my banking account twice( R4600 and R8 900). The first month this occurred, I did go to MTN to investigate on the matter but they informed me that no steps would be taken until I brought an affidavit. After queueing for a long time (due to Covid-19 regulations)at my bank and then at the MTN branch I had no time to stand in another queue at the police station.

I don't understand what difference an affidavit would make in investigating who was making debits on my account using MTN's name. Couldn't matters like this could be tackled without making the victim's life even more complicated?