Account cancelled and yet being debited (almost 2yrs later)

So I received a confirmation email from Najma Sallie on the 5th Jan 2016 ,confirming that my contract with Tracker has been cancelled as per my request. Never mind the issues I had with them for a refund after cancelling . Now tracker has gone and debited my account from Nov 2017 and this month as well.

What gives Tracker the right to debit my account a year and 11 months later ?

I called the call centre and Valencia advised that tracker shouldnt have debited my account ( Something which I know already but could not tell me why it happened when it shouldnt have).

I am now waiting on Finance to advise why this is the case and have been holding on for close to 5mins

I have reversed the amounts but have incurred bank charges thanks to the idiots who work with billing!!