Does a text from your operator constitute legal notification?

I just got a text in from Vodafone this morning as described here.

The text came ‘from’ Vodafone — that was the message identifier.

But you and I know that can be spoofed really easily. What would Vodafone do if I sent a text message to 500,000 of their customers saying ‘Good news, international roaming is now inclusive from midnight tonight’ and set the message sender to ‘Vodafone’?

Does a text message update constitute legal delivery of Vodafone’s message? *THEY* know they sent the message. They can trace the delivery through their network. But *I* don’t know whether it’s a genuine message or not. Do I need to wait until written notification arrives? Have I got any recourse with Vodafone if I act upon a message sent supposedly from them but actually from somebody else?

It’s at times like this when you have to think: SMS is pretty rubbish, isn’t it? Why is it ONLY 160 characters? Why hasn’t the industry upgraded the medium somehow to give some kind of certificate of authority, at least so you know that messages from your operator and bank are genuine?