Incorrect Billing

In August I changed my debit order details with Vodacom. I was told not to close the old chq acc with the bank in case it is not in time for the new acc. No d/o was deducted on the 1st Sept. I called and was informed that there is no explanation for the not debting my acc, but that they'll do a special run within 3 days to the correct acc. This didn't happen.I paid via EFT on the 8th Sept, the full amount outstanding as per the last statement. I then receive an sms 3 days later telling me I'm in arrears. Upon phoning they confirm that I'm not and that all payments are up to date. On 1 Oct my acc is debited with an amount far less than what is owed, again I have to pay the difference via EFT, but promised that it would be rectified. On 1 Nov my acc is debited again with the incorrect amount, far less than what it should be. Today I'm told I'm in arrears with a ridiculous amount because I did not pay my acc in July! When asked that they reconcile my acc and spot their mistakes, Noelle (consultant) says she'll sent statements to me to reconcile myself. It's been more than an hour and no statements or call yet. How does this happen and can someone please sort this out?