vodacom says account in arears but it is not

Dear Vodacom,

I received a message on my phone that I am due for an upgrade. When i checked online I got a message that there is a problem with my account and that I cannot upgrade. When i called accounts AI voice told me my account is in arrears with R383 rand. That is my normal monthly deduction and the last deduction was on 29 July as usual. I have not received any arrears notifications and how can I be in arrears if my next payment is only due 29 August? There is also no areas amount on the online bill, just the usual running amounts for this time of the month, Please advise what is wrong. To my knowledge I have not missed a debit order and if I did it does not show up anywhere and I have not received any notifications.