DOUBLE DEBIT FROM VODACOM

Vodacom processed a double debit on my account on the 31/12/2015. Due to this I had other debit orders that bounced, a sms was sent to advise me of this. When I phoned this morning to ask Vodacom to issue me with a letter/mail stating this to forward to my other service providers I was told that Vodacom doesn't issue these letters. The call centre agent stated that neither she nor her supervisor could issue such a letter and that I would get my refund today, and that I received an sms. Firstly it is totally ridiculous that they cannot provide an email or letter, and secondly that puts me in a bad credit situation with my other service providers. This service is totally unacceptable.