Gangsters in suits

I have been requesting that my account to be debited on the 25th of each month and should the 25th be on a Saturday or Sunday, for my account to be debited on Monday as I was advised that payments by debit only happen during the week. However, for two consecutive months my account has been debited before the 25, resulting in me incurring unpaid debits. I am not sure what language I should be using for this to be effected. In January this year, the right thing was done, but never again. Last month my account was again debited before my salary date and I have again incurred an unpaid debit. And now they are demanding that I make payment on the account. I requested that the debit order be cancelled and I pay manually, but even that was not welcome. Now I'm waiting on my devices' services to be terminated till the month again as they usually do. However, on the one end I am also incurring a very bad credit record, thanks to these people who won't even give a reference number when you request it.