Double billing - shocking customer care

Vodacom double-billed me. While I can understand that one can make a mistake, their absolutely pathetic handling of the matter is what angers me. I made a couple of calls to call centre only to get empty promises and different information from every contact centre agent! It is MY money that Vodacom *******y took from me after notifying them of the mistake prior to my debit order going. Why must I fight to get my money back especially after acknowledged they made a mistake. They clearly don't care. For many people a double billing like that can result in financial difficulty! Super frustrated and disappointed....