Amazingly, not all companies are the same. There are a few who do strive to implement "block lists" or "black lists" to prevent SMS SPAM.
In larger organizations there may be many possible sources of SMS messages. It has been our experience that the following companies take SMS SPAM seriously & have acted responsibly to quickly deal with the occasional lapse:
Telstra - Well done! Very fast to shut down problems at the source.
National Australia Bank (NAB) - Difficult in such a large & complex organization however definitely making a positive attempt to fix identified problems.