rotten customer service

I was returning my sons shoe at Woolworths in century city this morning a shoe I bought on the 27th April slip and everything with me, I was told i couldn't return the shoe because its dirty underneath I told the lady that my son only fitted the shoe he didn't wear it outside when i saw it was too tight he took it off, The manager by the name of Norma came n she said I must see what ill do with the shoe as she wont take it...Here's the thing with Woolworths when ever a black person is returning something they ALWAYS find the smallest thing not to take back the item many black people are having the same issue does your policy only apply to white people? I will be keeping the shoe its fine but i will never ever buy anything at your stores ever again including my family, IM REALLY DISGUSTED.