Business Account frozen without any reason!

As a school we have a business account with FNB. <br> <br> Yesterday morning our account was frozen without any notice. After calling the contact centre we were referred to the branch. The branch checked all documentation and could not find any reason why the account was frozen. They also could not \unfreeze"the account. They said they would take it up with head office but that we should also try the call centre.<br> <br> We have called the call centre numerous times and spoken to many people"