Nedbank letters does not correspond with debit order

Good day so we received a letter from Nedbank homeloans on the 21/11/2025 that our debit order for nedbank has change from R10290.14 to R9818.97 and it will take affect from 1/12/2025 the debit order that went off was still R10290.14 and then in January 2026 R10000 was in the bank were the debit order goes off and it bounced ... please tell me does Nedbank not work according to their own letters or does it just not get done or is there no communication between departments , so i emailed Lucia at Nedbank and she said a totally different amount that is on the letter R10017 shoulcd be debited. Please keep in mind that i have done a eft transfer on the 30/1/2026 for R9820.00 that was more that the letter said and now it is with collections , please explain this to me as what is on the letter should be debited not another made up amount !