Pay DOUBLE FOR GOODS NOT IN STOCK !!!!

I purchased goods from Makro online and some items were not available in stock. They sent a notification that they would refund me for the 3 items. I received 2 refunds and 1 item they charged me again for the same item. Thus I paid double for non item in stock. Hello !!! how does that work out? I sent proof of the matter and was contacted and told to send proof via my Bank account. ( The statement has all my financial information, my account, etc !!!!) I asked them to check their records and proof of payment. Well I cannot make out head or tail how these refunds work, not straightforward) I managed to blank out the crucial info.