Telkom and the suspension of ADSL which has been paid for

I cancelled my voice line online last year and received a reference number which made me assume that it was all done. Recently my ADSL was suspended because of "non-payment" of the account which I cancelled. There is no way to get hold of anyone at Telkom who is willing or able to assist and my frustration is huge. My ADSL rental is paid, so how can it be okay for it to be suspended over another account?