Bad quality on toughees shoes

I bought a toughees school shoe for my son from Edgar's on 29th July 2018. It has a tag with a six month gaurantee for fair wear and Tear. I took it back the 26th November as the stitching coming loose and breaking by the side.He only had it 4 months, very disappointed with the shoes. Edgar's refuses to return it, as they say gaurantee is only on the upper outside of the shoe. I am very disappointed. Why put the words gaurantee on " fair wear and tear" if they do not one to exchange. Paying so much money for a shoe that he wore for 4 months is unacceptable. I hope u can assist me with my problem. Awaiting for your feedback.