Received the promotion sms a week ago. Recharged with R1200 on Sunday, 26th Feb 2012. 24 hours later and no 50% recharge bonus received. Called the call centre & logged a complaint. Seems like this might be something worth reporting to the CPA and / or the ASA for false / misleading advertising and touting.
Update: After logging a complaint, the bonus airtime was received within a few days. Result: R1800 worth airtime for R1200.