threatining with legal action

There is an unknown bank debit order from my absa bank account since october 2015.from there on every month end I had to go to the bank and reverse the payment of 399 from loan locators.Now out of the blue I have been receiving massages on my cellphone and Email threatning me with legal action and I have also been receiving a letter of demand saying that I have to make a payment of 1527.50 which isdue by 2016-01-20.When I ask them to send me the proof agreement whereby I have signed the agreement they say that when I apply on and click 'accept' int means I have automatically agreed to everything.<br> <br> <br> I had a look at the website for loan locator - itb does not specify what does a cperson actually apply for instead it shows the different quotes for a loan.