Standard Bank does not respond

I've been receiving notifications from Standard Bank via SMS about a Standard Bank account that is overdrawn. I do not have any accounts with Standard Bank, so I phoned them a few weeks ago to advise them. The call centre agent was apologetic and took all the details from me about these messages. While I was on the line with him, he went onto the bank's computer system and made a note to the effect that the bank should stop sending messages to the mobile number they have on record for the account because it is incorrect.

Despite this, the messages continue to come to me. I have also gone online on the Standard Bank website to lodge a complaint. I have not received an acknowledgement of my complaint and the messages continue to be sent to me.

Will no one at Standard Bank do the necessary? It frustrates me enormously that I took the trouble at personal expense to notify the bank but they have not done what should be done. These SMS must surely be a cost to the bank so why don't they stop sending them?