Business Account Frozen without notice

Fnb ***** department decided to freeze my business account 15 May 2018. My question is how do you freeze an account business account mind you without contacting the business? If i was to go to a bank and tell them I paid a retailer(Pick n Pay) so much and he didn't refund me are you just going to freeze their account without contacting them to see what steps were taken to resolve the issue with the customer. I contacted Fnb they said an investigator will contact me within 48 hours but today its the 18th. Why is your feedback to clients to poor? Please unfreeze my money so I can take my business where it is welcomed.