Return unfairly rejected

I bought a pair of Adidas sneakers on Zando on 03/04, it was delivered on 05/04. I IMMEDIATELY, after trying on one of the shoes (with socks on) logged a return. The shoes stayed in the box in my office from Friday to Monday, when it was collected by a courier. On Tuesday 09/04, I was called by Zando to say my return was rejected because the shoes were in an unsellable condition (a scuff mark on the inside). My guess is that they have already paid Adidas for this pair, is now refusing to refund me and will definitely be selling them again (and again and again) - possibly hoping to rob another customer(s). From what I read here now, it seems Zando is not too keen to refund for purchases. DO NOT BUT FROM ZANDO UNLESS YOU ARE ***% SURE. Not even if it is the last place you can find something.