Haven't received my return 7 days after an IT34 was issued

I submitted my tax stuff on SARS eFilling exactly 7 days ago today. SARS responded promptly with an IT34 notice, which indicated that I'm due to receive a tax return (which was a negative amount, not sure what that means. Do I owe SARS or do they owe me?). Now I still haven't received the money (7 days later). What could be the problem?

The negative amount means a refund. You need to please call SARS on 0800 00 7277 as it could be that you have outstanding tax returns from previous years.