Double debits, different days

Double debits and no one can sort it out. My account was debited twice in October 2020 for R490 x2, in November the debit order never went off because it went off twice in October 2020. Now in December, it went off again R490 on the 21st of December and again R490 on the 31st of December again. When I call or speak to agents they tell me it was because November 2020 wasnt paid but it wasn't paid because you took R490 TWICE in October. They then tell me they will call me back. This is ridiculous!! I've been fighting this since the 31st of December and still no way forward. How can you debit me when you feel like debiting me and then you still debit me twice?? Take your money once a month as arranged as I have not budgeted to pay twice for one month. I expect FNB to reverse the R490 that went off the 2nd time on the 31st of December as they already took December payment on the 21st of December. Then I need to start being debited correctly, once a month on the 25th or 26th of every month. The dates you debit is different days every month then I need to pay bounced penalties. Can we please resolve this once and for all...