Bank charges incurred

In December 2015 Vodacom ran a double debit on all their clients banking accounts and because I only had funds in my bank account for 1 debit the bank sent the 2nd debit order back as unpaid and I was charged R115.00 for having insufficient funds in my account for this 2nd debit order. I contacted Vodacom to inform them about this and I was informed by the accounts person to send a copy of my bank statement as proof of the bank charges incurred I did this on 11/01/2016 and was promised it will take 14 working days to be refunded Now whenever I call Vodacom I can never get through to the accounts department and the call centre agents just informs me they cannot access the accounts screens Why is it now so difficult to speak to the accounts department since I need a refund? I guess I must accept because of Vodacom's incompetence in the 1st place doing double debits I have been ****** of a R115.00 and my credit scoring affected because of this unpaid debit order on my banking profile?