Paying your FNB Credit card before the due date = credit card to become in arrears??

FNB really don't seem to know how payments work when it comes to credit cards. I spent almost an hour on the phone with their agents and nobody seems to understand what they are doing.

I receive an SMS each month on the 22nd or 23rd which indicates what I still owe and that the minimum amount of Rxx is due by the 15th of the FOLLOWING month (Keep this in mind). So, the SMS dated 23 May 2025 stated that the minimum amount is due on 15 June 2025.

I've always paid either on the day of the SMS or the day after the SMS via manual payment. According to my bank statements, the payments are received and allocated to straight and budget.

On 23rd June 2025, I received an SMS stating that they didn't receive a payment and that I'm in arrears - which is odd, because I paid the minimum due before the due date.

I Spent an hour on the phone with 3 different people - the first one was rude and insisted that I don't understand how credit cards work (I'll get into that later) and the last two contradicted the SMS (and simple logic).

SIMPLE LOGIC: If payment is due by the 15th of each following month (as per the SMS) and I pay before the said date, I should be up to date.

FNB LOGIC: I paid before the due date and thus the payment doesn't "count". I mean really. ***?

The three agents insisted that I had to WAIT until the 15th of each following month to make the payment and that "paying before the due date" wasn't seen as paying the instalment or paying the minimum due, but was considered an "additional payment" and that I still needed to pay the amount due.

So if this is truly the case (that FNB's systems are unable to allocate payments if they are paid before the due date), then why on earth has this never been a problem? I've been paying before the due date for well over 2 years. It's NEVER been a problem, but all of a sudden I'm in arrears?

SIMPLE LOGIC: Paying before due date = account is current FNB LOGIC: Paying before the due date = bad. We don't acknowledge this as a payment.

The sheer lack of common sense is shocking and I mean this is an institution we entrust with OUR money, but they don't have common logic when it comes to allocating payments.

How can I be penalized for paying BEFORE the due date. I mean, I can understand paying after the date, but BEFORE??