Was in Australia last month and had Global Roaming Off on my Vodafone phone. Received a text and replied to it. This incurred the $5 roaming fee plus 17c for the text. Is the $5 roaming fee charged for sending or receiving a text message even when data roaming is off? Shouldn't a warning be given first before the text is sent?

I know it's no big amount but when data roaming is off no text should be able to be sent or are texts an exception and only phone calls and data are blocked?