Still debiting me after paying R1700 for cancellation

I paid for their sign up fee. Got no service from them. Takes on average 30 to 40mins to get a hold of them. I canceled and payed a claw back feels of R1700. Sent the proof of payment. They've collected their router. I thought finally all the stress they have caused us for 2 months is over and then last night they debited me again. Worst ISP ever.