Tread Miller Shoe damage

I bought a shoe at Tread Miller Walmer Park It didn't even last for 6 months it got torned Bare in mind how expensive their clothes are when I returned it they said I must bring the Slip I told how am I suppose to keep the slip for 6 months, more especially when you trust the rare earth Brand and I buy their expensive shoes on purpose knowing that they will last so I don't see the point of keeping the slip.

My help me get refund or exchange for that shoe.