I had a "discussion" about this with Vodafone when I started using them a few years back - I was being charged £1.25 per text for receiving advertising texts! They can switch it off at their end, in my case with an innocent "Oh, don't you want adverts sent to your phone" - "NO, it's for emergencies only, I'm usually driving, and what makes Vodafone think I want to pay for them anyway". End of conversation, end of texts.