Incorrect billing and incorrect billing investigation

I paid with credit card in full my outstanding balance before upgrading my contract with sale consultant Jade Jewell Cellucity Vodacom in Canal walk, Cape Town, R1381.41 on 12 October. The date on which the debit order supposed to go was 25 October. This consultant told me it will be cancelled because I paid in full. Then, on 25 October the debit order went on and the SAME amount was taken. When I called to Cellucity I've been told it will be investigating. Then when no reply was given, I called again in few days, and asked for their Head Office. 3 times I was cut off. Then one lady told me she doesn't know their head office number. Then I received sms about investigatin result but somehow they counted this amount twice. I will never renew my contract with Vodacom again and advice no too deal with them, You will call them hundred times and nothing is done.