Incompatible suggestions by website

I bought two projectors and projector holders that where suggested by the website which turned out to be incompatible. I requested a return of one of the items and the supplier declined even after i SUGGESTED THAT I dont mind exchanging for items compatible with the holders holders. They only allow refunds within 53 days but I had no reason to return the items because we opened them when they where needed only to realise items suggested by their own website where incompatible. They dont even provide the suppliers details for me to communicate directly with them for exchange.