HARASSMENT BY BUCO

For months and months I have been receiving annoying sms messages from BUCO offering me specials. On more than 5 occasions I have called their local manager, Ettiene, on ********** , at their George branch, requestng him to take my name off their sms list. Every time he promises me faithfully that I will receive no more messages. Again yesterday I received another sms from BUCO. What am I supposed to do to stop this invasion of my privicy ?