Absolutely unacceptable

First of all, I have never bought anything from Street Sheet or given any permission for money to be added to my account. I went to the Centurion Mall store and I gave the Lady my Affidavit and Documentation pertaining to the so-called money I owe. I don't even know what the account number is supposed to be. I went online and created an account under my name and it states I owe nothing. But still, I keep getting the following SMS's:

"We did not receive payment on your Sheet Street account which is in arrears. Please pay R1545 to bring your account up to date or call ***"

"Urgent Reminder: We have still not received the payment of R 1,545.00 on your Sheet Street account. Pay today or contact us urgently ***"

How can a company allow an account to be opened without permission or signature or some sort of security measure?