Standard bank not paying their creditors?! How is this possible!!!

We did work on a property belonging to Standard bank, but is now struggling to get payment. ISF Construction Services (Pty) Ltd is one of Standard Bank's suppliers. We provided a service at an extremely competitive rate and the reason we are now getting for non payment of our account is that Standard bank is not paying them. This is not acceptable. Standard was enriched by the work done on their property and now is failing to pay their creditors. I am sure Standard bank will not let any of their customers get away with not paying their accounts. Why are they not paying their accounts? Wendy Smit from ISF Construction Services (Pty) Ltd has been in contact with Standard bank and according to her the monies owing by Standard bank is still not reflecting in their account. How can a bank not pay their creditors? We are now considering planning a protest action in front of the farm belonging to Standard bank if we do not get our proof of payment before the end of this week.