Hello 'jose_plan',
There are only 2 things you can do: send them back at great expense, or keep them and learn from experience.
Perhaps you can resell them if they are usable but simply the wrong size.
This is one of the disadvantages to buying overseas. If there is a problem, it's beastly expensive to mail the item back.
If you choose to do so you will need to send it with Delivery Confirmation, or else your seller will surely say the
parcel never arrived.
Not only that, but you will need to open a case in the Resolution Center within 45 days from when you bought it.
You must not let that deadline pass. The following link will tell you all about opening cases:
http://pages.ebay.ca/help/buy/item-not-received.html#steps
Sometimes a seller will stall a person with promises of a refund, just to delay past that day 45, when it is too late
to do anything about it.
If you are wondering what it might cost to mail it back, if you know the weight and dimensions you can find out
here (be sure to use metric, otherwise you may not get an accurate result):
http://www.postescanada.ca/cpotools/apps/far/personal/findARate?execution=e1s1
Otherwise, there is nothing more for it. Sometimes it is better to buy locally where you can take your tape
measure with you, and if you need to return an item it is not nearly so far.
I wish you all the best. 
