TELKOM -Refuse to refund me

Telkom instuct Nudebt to debit my account without notifying client and arrangements were done with telkom contract was cancelled withing 1 and a half month with telkom and i was told im liable to pay the rooter R1800.00 I made arrangements to pay through easypay and it was accepted never skipped my payments but Nudebt ran debit order on my bank account I requested a refund and was told no refund will be generated bad ,bad service