FNB threatening to freeze account for docs on a 5+ year old account

FNB requesting documents supposedly for FICA reasons. The account was opened more than 5 years ago and 4 odd years into the account, they request new documentation (proof of residence, source of income?? and copy ID). Submit documents during November and lo and behold, come Feb, they need new documents, otherwise they freeze the account!!!! There is most definately not enough money going through this account for all this hubbub. And any request for feedback is met with generic it is for FICA purposes answers. If they freeze this account, my sons studies and my rent will not be paid. Thanks FNB