Like others said double insoles extra socks is about all you can do. I would suggest tryig to exchange them honestly if you try any of the soaking them in water tricks to shrink them you could ruin them.
Doubling your sock is the only way I can think. Shoes can't be resized, unfortunately. That online shop should allow items to be returned for sizing fail purposes. It's a common offer to all online shops. Try to ask or call them :) Keep the receipt
Try putting in another pair of insoles or doubling up on socks