Ripped off

I was charged 10% handling fee having bought a basin on Friday 7 Aug returned on Tuesday 11 Aug (box (unopened),also I picked it up from suppliers warehouse so they did not even handle it! Was told the supplier charges them so I must be charged. When buying from a competitor store I was told the supplier does not charge handling fees! This is unlawful (CPA) !! Will now lodge complaint with Consumer council