Unprofessional service, below the bottom of the bucket

We opened an account with Sterns and paid within 3 months. The lady who assisted us advised to take a 6 months contract because it is interest free which we did. After 1yr 4mnths we receive threatening calls and sms's that we must come and pay, when we dispute it and request for payment history they say they destroy our files after 3 months and they are not able to go back further to confirm the owing amount, so we must pay R2700 and odd rands. They say they have been sending us magazines which costs over R60, emails and over R20 per communication. Apparently 6 months interest free is changed to 12 months. Customer care is unable to help, we went to the branch they referred us back to Customer care, and the manager there also was not willing to help also refered us to customer care line. They claimed their phones are not working to phone customer care line as they cannot do anything on their side. No one is taking ownership to assist, all they want is money. They are not able to provide a simple payment history all they want is money. How can communication sent out costs R2700 in a year, and they did not send communications monthly. First time I come across something like this. They have a nerve to say "I dont know" . Who must know now, a customer? Its December now they want to reap us off. I used to love Sterns, but this.....