CUSTOMER NEGLIGENCE

I bought a shoe on the 25/01/2020 at Evaton mall. I wore that shoe once and realized that the strip of the shoe is torn a bit. I went on the 01/02/2020 which was 7 days later after the purchase to return the shoe as I'm not satisfied. When I got there they told me they don't see any damaged and when they call the head office they won't even be able to explain the damage. So I asked them what must I do with the shoe, they told me I have up to 6 months to return the shoe so meaning I should wear that shoe up until the whole strip tears? I think this is customer negligence.