Accounting irregularities

I subscribed to Kleen-bin some months back and have always prided myself on paying all my financial commitments on the day I receive my salary - at the very time I receive my salary. I pay between 23rd and 25th of each month as soon as my salary is paid in. Kleen-bin only sends invoices at the beginning of each new month and services are paid for in arrears. I was so surprised and highly annoyed at receiving an invoice this month which stated that my account is 2 months' in arrears ! I immediately responded requesting that the error to corrected. To date I have received no further correspondence and no apology for the error. I have emailed them to terminate the service.