Unable to change personal loan debit order date

I need to change the date on which the debit order will be deducted from my account, which they erroneously set to the 28th. My salary is deposited the first.

I am now told that I need to send a "letter from HR" stating that I receive my salary on the 1st. Our "HR" is notoriously slow and by the time I get this so-called "letter from HR," the debit order would have been deducted.

This is a backward practice! Why cant they just change the date? I have done my banking with FNB for years and my transaction history is open to them.

Pity I need to resort to Hellopeter.