Billing Error, then Intransigence

I have been a victim of a billing error by Vodacom. They have erroneously debited my account twice for the same month, within a period of 4 days.<br> <br> I've alerted them to this, which they have acknowledged and undertaken to rectify. During the course of their investigation, I've authenticated myself to them to prove I am who I say I am. Now, you would expect someone who has wronged you to speedily rectify the matter without any further hassles. But not Vodacom. Instead of simply refunding me, they have come back with an additional requirement of my having to fax them my bank statement reflecting this duplication to prove that this billing error indeed took place. This is information that is available to them, which they have verified in the course of their investigation. So why prolong the matter? It is bad enough that I have to wait for up to 14 working days for them to sort out their mess. <br> <br> I'm being told that this is a requirement from their accounts division for escalation. Would they do the same if I had asked for an account credit? Seeing they've seen this error, surely they should rectify it without any further inconvenience. All I want is for them to pay back the money.