Unsolicited, unwanted, unstoppable marketing SMSes from Woolworths

I use to have a Woolworths card, but I got fed up with constant SMSes so returned it instore, asked customer service to cancel it and STOP with their SMSes. They reduced in frequency, but I still receive them several years later. I received one today prompting this negative post. Sending an opt out SMS involves the (small) cost of the message, but only stops them for a short period. I'm on the WASPA "Do not contact" list but that also has no effect.