It's to do with the free 2GB weekends.
Every Friday 2 texts are sent, one to say it's getting close to start of 2GB, and another shortly after to say it's here.
From what I can see the act does not mention about repetitive messages.
I use some of the data so I'm happy for trade off of two texts, for the free data, but I can see for others how it would be over top.
If I was upset I'd still complain to DIA, let them interpret the law.
Edit: Just went through texts, it's one text a week. Just the one nearly here.