Just to clarify, if people are getting confused as to why some networks seem to get spammed with these texts and some don't; mobile numbers are assigned to networks in batches. I work for a company related to telecoms and we have a list of all the codes and which network they belong to; for example, 07409 falls under Orange, 07507 falls under T-Mobile, 07810 falls under Vodafone, and all numbers stemming from that are of that network. It's possible, and likely, that they dial the numbers in batches, in such a way that they all go to the same network. Of course, this varies if you've had the number ported.
Hate to add to this but these numbers call LANDLINE numbers randomly and leave automated messages . .Going to ditch your landline provider too? I have friends on all mobile servers except '3' . . .we all do the same, delete (or if their phone allows then 'block') the message and just drop our providers a courtesy email to let give them the number. My hubby generally gets one a month and he's on Orange!! Maybe you should try reading the small print on every 'contract' you have. Or just get down from your high horse. If all you have 'wrong' is receiving a few 'unwanted' calls/texts then your one of the lucky ones in the world.