Return policy differs

I bought T shirt Online, unfortunately one was too big.I first read the return policy and went to the store at Lenasia to exchange.I was told Online purchases are a problem to exchange, they need a hard copy of invoice.I ask to email it to them , they said no ,they email is for the store only.I had to go to find an internet Cafe and print the invoice.This was my first time purchasing at Lenasia ,worse service ever.I asked were is it written that a hard copy is needed, no answer , they told me it's their rules and takkies town Online return policy and store policy are not the same.they did not even have name tags on ...I was served by Mpho and another lady at the teller...