Ridiculous interest every month yeYET they refusing to provide with a details statement!!!! ..

I have a credit card with Standard Bank ,It got handed over to Attorney without my knowledge,no letter of demand was sent to me...I was called by Mc ******ts advised it was handed to them,I am self employed and made arrangements to pay R1200 every month however they charge interest every month not sure why because interest should be charged once according to the law,I requested numerous times for a breakdown Statement or Reconciliation they are refusing as balance doesn't decrease .Recently i got a letter from Standard bank stating account withdrawn and back with Standard bank I went to the Branch and they know nothing about the letter ..I am confused as to what is going on here ...i need a clear explanation