Refusal for exchange

I ordered shoes as a birthday present for my partner who's birthday is towards the end of December. I ordered the shoes mid November to avoid the festive season congestion. Upon giving him the gift, I found that the shoes were too big for him even though they are his normal size. There was no warning on the Superbalist website that the sizing ran up to two sizes too big! Now I am sitting with a pair of shoes that cannot be used, when it would have been so simple to just exchange them for a smaller size. I feel that they could have accommodated me but they chose not to. I mean what is the big deal? I just do not get it.