Handed over for their error

A year ago I changed my bank account and went into a direct Vodacom store to arrange the change in debit order details. I chose the 27th as the debit date. Expecting a problem for the last debit on the old bank I paid cash for one instalment. The first debit went through on the 26th which included a R100 late payment charge and it bounced. The next on the 25th for 2 months contract and 2 late payment fees and bounced. Having had no internet I went into the store to query and they said that there were no payments. My bank statement revealed the problem. I went into the store paid for 3 months worth of contract (for which I had no internet ) and asked for the late payment fees to be reversed as it was a Vodacom error and for the debit date to be corrected. No reversal of late payment fees were raised and a forth month of no service was billed to my account but no further debit order was raised. When called by Vodacom I explained their error had caused the bounced payments but I had paid three months already and would only pay when the service was resumed. Still no reversal and no service. Six months later two invoices are raised and a collection demand. to which I responded with the explanation of the balance and the debit date error providing proof of debit date and payment of 3 months contract fees. After more demands and more explantions only 2 late payment fees are eventually reversed at the end of last month. But more demands for the balance and with termination fees and other costs now amounting to 4 times the contract fees and presumably legal fees adding on each time with the latest and sms threat of sheriffs etc. After 6 years a good customer, paying for 3 months of no service for vodacoms error am I still to pay even after a year of no service?