Getting bill for prepaid/cancelled line

After a ********** update on my data line in Dec, it was finally cancelled and transferred to a prepaid line on 23 Feb. I was told at the time that because of the inconvenience of not being able to use my data for about 2 months, they would leave the data on the card for me to finish, after which I can choose to put more data on or not. 2-3 months went by of me using data, and then all of a sudden the debit order amount that went off my bank account, was more than my bill. When enquiring, I was told that it was for the prepaid line, customer services could see that the line is a prepaid line, therefore referred me to accounts, who referred me to retentions, who referred me back to accounts, who referred me back to retentions, etc etc.<br> On 9 June I spoke to Daniel in ***** department, who sent a mail to retentions department to advise them to sort the matter out, as it was ***** case and line should not be billed. I was also promised that I would be phoned within 24 hours after I also logged a Service request. I am still waiting and in the interim R500 was taken off my account, and another R4500 waiting to be taken off at the end of this month. I cannot seem to get joy at all!