You could try to sell them yourself.
If items don't fit, then that is counted as a 'change of mind' return and you do have to pay the postage.
Shoes are, I think, especially tricky to buy online. Even if you always buy the same size from a same brand, a particular range or style may not fit your feet.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)