FNB IS A HUGE PROBLEM!!!

My account has been blocked due to *****elant activities that I have no idea of. Apparently did I myself log the ***** complaint but I have no knowledge of such cos now they asking for case nr, affidavit, ect... What is happening with fnb to just block my account without notice... I can't even use my funds in my account... Today again they've sent a email requesting a case nr from Saps... These people is crazy