Rain internet network

I have been on Rain network from late last year. My May debit order was not debited and they apparently tried debiting on 25 May and there was no money on my account and they subsequently switched off my account. i called them on 28 May to cancel the contract and i was told to pay first and i said to the operator since they are going to debit on the first i would then cancel it. They have not debited anything again and when i tried to cancel it they told me i am owing them R1 200+ and can only cancel when i pay. i have not paid for May only and have not used their service for June according to me i am owing them only one month. they failed to debit and asking me to pay and not even giving me an account number.