Harassment from Fnb housing

Fnb finance keeps on calling me and sending threatening messages to me, they are asking me to send them my details which are confidential like my I'd copies, banking details and addresses but when I ask them, they fail to explain, they just is for our bond, however my husband is the one paying for and they don't call him and we not even in arrears, so they threatening to stop our bond of which support to date and as for my I will not provide until I am given a valid reason as I don't even understand why they are telling me about FICA and updating my details where else they ca my husband