Wrong size right tag

I am really not happy with the mistake that woolies employees did that cost me, I went to buy the tummy g-string at woollies in Mall of Africa early this month if not late last month I wanted medium I bought medium according to my knowledge because the tag was saying medium to my surprise when I wear one of them the medium was big and when I check the label on the panty it says large, I bought 2 of them mind you at the price of R149 each when I return one of them to my nearest woolies store I am being told they can't help even after I told them that the mistake it's not mine it's theirs the y showed me the return rules and they told me I must take them to the woollies where I bought them and I was like so I must drive 59km just to go and bring this matter and the mistake to thier attention whereas it's the same store