Cancelled in March and still being Debited

I have sent emails, i have made calls and still i seem to be debited for my adsl line rental! I cancelled this service in March 2015 and to date im still being debited R206.00 a month, my reference number to this is AI***. Now i would like this to be sorted out once and for all and i want my refunds back for the Months you ****** are debiting me!