Whats happening at ADT account Department?

I cancelled my ADT contract in the beginning of 2014 because of money difficulties, ADT then send a technician to my property to remove the Radio sender/Receiver. 2-3 Weeks ago I received an SMS stating that Your ADT account is owing R210.14 and has been handed to Debtsource for collection. ADT Accounts Department could not say what the money was for but confirmed that my outstanding amount is R210.14 and that I must contact Debtsource for more information. Debtsource confirmed that the outstanding amount is R210.14, but they could not say what it was for. The 11th of October 2015 I received a \Letter of Demand"from Debtsource stating that I suddenly owed ADT R3710.14. Lekker man! I would like to know from ADT how can they hand me over to a debt collector if I have not received any correspondence from them to the effect that I owe them any money for over 1 and a half years? How can ADT and Debtsource confirm the amount of R210.14 per SMS and per phone and then send me a letter of demand for R3710.14? Lastly"