Refusing to Exchange after Sale -

HI,<br> <br> on Sunday 29th Nov 15 i purchased two kids shoes from the greenstone branch, the store had a sale buy two shoes for the price of one.<br> <br> I asked the people in the store whats the catch and i was told that you pay for the most expensive shoe and get the cheaper one free, i was happy and purchased it,<br> <br> I bought these shoes for my Two nephews, when i get home we discovered that my one nephew already has this light up sketchers so i decided i will exchange the one pair for a adult shoe for me and i will pay in the difference since the adults shoe is more.<br> <br> i was in rosebank and tried to exchange this, the store told me that only greenstone can do this exchange since it was a sale item, they called green-stone and told them to keep the shoe i wanted for me, the next day i go to greenstone and the store tells me that there is no return or exchange on sale items, i said but no one told me this, where is the policy displayed for customers to see this, he tells me its at the bottom of the till slip, i then ask him how will that help a customer to know the policy if its only provided to us after transaction takes place, <br> <br> Please can sketchers call me urgently to deal with this,