On their official website, they have written that:
To Fully Block ALL PROMOTIONAL Alerts (SMS and OBD)
- OPTION 1 : Type PROMO OFF and SMS to 678
- OPTION 2 : Call our 24 HOUR Hotline at 1777 and speak to our contact center agent
For this fully blocked category, customer will NOT receive any promotional calls or SMS to the mobile number registered for this service.