Neotel Robbing us even after they terminated their service

We got email notification that Neotel will be cancelling their services from the 31st May. To my surprise in may i was debited over R1600 and was told its out of bundle which was not correct When i queried this, i was told this was an error on their side but i still have to pay over R170 for June. I fail ti=o understand what im paying for when you terminated your service on the 31st of may