Debit order complaint

I received a disturbing sms this morning to say that my card payment is overdue. Discovery debits me at the end/beginning of every month and for you to say that is not on. If you guys did not debit my account please do not make it my issue as I chose this preferred method of payment for a reason. I now get an SMS saying that I must pay double the amount, and I must pay it immediately. Why wasn't my account debited specifically in this month? You will need to fund that amount yourself as I am not in the wrong here and you are messing up my credit record for no reason. I am very disappointed