Refund issue

The customer service at Vodacom is very poor I am complaining again for the 2nd time in a month! I have sent an email to refunds @vodacom , pop@vodacom , pnr@vodacom for weeks now. The amount they refunded is now showing on my bank account as a minus. When I go to the store I made payment they telling me its an accounts department issue when I call different consultants are telling me different response. How can the amount they claim to be refunded come back to show as a minus on my bank account . I am really tired of Vodacom not solving my refund issue for a month now !