Cancelling of unauthorised debit order

Since I made a call to FNB Premium account close to a month (17 Oct) about a certain transaction in my account of R8.00 that is taken almost everyday. I tried checking where does it come from but to no success. I got a feedback through voicecall that they will investigate the matter & in 05 working days I’ll get a feedback. Now is more than 21 working days but still not hearing anything from this bank and my account is busy debited…mara why? What for? I was happy with FNB before but now I think is time to move to another bank because before I had almost the same problem with my previous bank. I’m giving them 14 working days then I’m done.