Great service until I cancelled my Rental :(

I have had such fantastic service from Rent A Store up until I cancelled my rental with them. I confirmed via email to cancel my unit from end of February 2016. They were fantastic and gave me a courtesy call a few days before the end of February. In this call I told them that I had cleared the unit at the beginning of February already however it would not be convenient for me to come to the unit and that they could cut the lock. I unfortunately forgot that the debit order was cancelled and that I had to make a manual payment to them for the last month of rental so I'm totally at fault for this. In March I received another phone call asking if I had cleared my unit and if they could cut the lock. I rep**** that I had made it clear previously that they should cut the lock. In April 2016, I was charged R3,120. I still don't know why this was the case. I had a horrible discussion with the manager where I lost my temper because she took the view that I was wrong and that everything was my fault because I didn't send an email for any of the above and the system did not show what I had instructed them to do. It is now May 2016 and I've just been charged another R1,380 even though I cancelled my unit for end of February. Very disappointed in the treatment that I have received from the Midrand team.