personally think its one of those marketing things were if you text back they reallise the phone is active and send loads of advertising messages and other crap. if you think your entitled to compensation ring up your insurance company or go to your local c.a.b and see what they have to say, personally if i was going to be making a claim ide be using a company with a reputation rather than a company that sends out texts on a random mobile number (bare in mind most companies number doesent come up when you get a text it says the companie name, i.e just got a text off halfords saying my online purchase has been sucessfull and in my inbox it comes up as "halfords" even though i havent got there number saved ect.)
