unprofound billing and callous illtreatment

In february I called cellc asking for a settlement amount.The agent informed me that the amount will include february's amount.I settled it.Called 3 days later to confirm recipt of payment. The agent said its reflecting.March and April they debited and I retracted the funds. April they put airtime on my phone.I called in and they told me my contract hadn't been cancelled because I used one reference of which I wasn't informed. It took me a full month to have the contract cancelled. Now we are in May and cellc has billed me again and claim the contract hasn't been cancelled.I spoke to the most vile agent who gave me a **** manager to speak too Tumelo Ndebele who said that because I used the airtime I owed them.But I wasn't aware that they had put airtime on my phone because I bought my own prepaid airtime. And also I had not asked them too.And the fee is ridiculous because at first they said the other phone is paid up and it did not have airtime.I refuse to pay this bill as I had paid all the amounts requested of me and I never asked cellc to put airtime and they also refuse to send a paid up letter.They say they called , but on a wong mobile so whose to blame.