Sterns white gold rings that discolour after 2weeks

I am not happy at all can someone educate me here we bought a wedding ring at Sterns a white gold ring it was going for 25999 and they were running a 50% discount so we bought the ring and my wedding was on the 30th of April 2021 2weeks after my wedding I noticed a discolouring on my ring I went back to Canal walk where we bought it gues the shocking response I got they said it wear and tear like seriously after 2weeks I've already damaged my ring They said they where not going to take back the ring or refund they can only re polish it and quote me for that.so they booked in today back to the manufacturer its so shocking after care service