Liberty Life

On the 6th of October 2023, I phoned Liberty to change my banking and debit order details, subsequently a debit order was raised for the same day resulting in an unpaid item on my bank account as my salary has not been paid into that account yet. When querying this I got the reply that the debit order that went of on the 2nd of October was for the month of September - meaning that it gets billed in arrears, logically speaking then, the next debit order on the 6th of November should be for the month of October correct? No, not correct, because according to the e-mail I received, I am now in arrears with one premium for the month of October. This is the reply I got: "Kindly note that the policy is paid to date 03/10/2023, which means the October premium is still outstanding. The debit of 02/10/2023 was for the month of September 2023" I am seriously confused, if I never changed my banking and debit order details, would I then still have been in arrears? Nobody contacted me to inform me I am in arrears, so what is the difference now.