Valuating the tenets rights

As per my contract with Zelri regarding debit order its every month on the 25th , they debit as per agreement, no miss out of monthly no complains nothing , i discovered that my mobile banking was not working but i could not go to the bank to resolve my mobile banking , due to work , on the 26th of August 2020 , i decided i asked for accounts department , where i addressed my mobile banking, spoke to Igret Loots to check if the money was deducted , she told me that she will check and get back to me , i repeatedly her if she is under accounts she said yes, i was confused if she is under account why she cant see payment was made , she says she has my details she will call me before the end of the business , she never did assuming i never miss a payment so it means all is well , then a week after i receive an sms at 17:09 pm saying i have an outstanding balance of my rent, , next day i call she says its not their fault, that their translations debit order went on the late. no record that i skip and their are the first on my list to deduct , i told igrid Loots that i can make arrangement to pay that money, but they can continue to deduct as per agreement , she said she will call me as per her empty promises ,today i receive a letter of demand from her,. i feel that Zelri was unprofessional , Igrit Loots needs to be trained she is coursing a conflict