how would I know that a payment without receipt printed at AXS stations means payment not made, even though transaction is succesful?

quite agitated when I saw late charge in this month's credit card statement as I remembered clearly I paid my last month's charges in time (a few days in advance!) at the AXS station in my office building. the person before me who used that machine warned me that the machine didn't print out receipts. I still made the payment anyway and didn't bother to check if deduction was indeed made to my saving account. tsk!

after several attempts calling the bank's hotline, I managed to speak to the phone banker (their term, not mine) and had my late charge waived.. otherwise I'd have asked for cancellation.