Why should I pay for a manufacturing default

So I placed an order for the 18-piece Manhatten Bedding set, which was not cheap, I previously ordered the curtains, because my windows are more than the amount of curtains you get. This weekend we decided to take the blinds off and put the curtains on, to my surprise one of the curtains are shorter than the rest you can imagine what that looks like. I phoned homechoice this morning trying to reach an conclusion as to what to do about this. To my surprise they are not willing to do anything from their side, and this is actually their mistake and not mine. I was advised to send the curtains back on my expense to have it evaluated, why must I now pay their mistake and what am I supposed to hang in front of my windows seeing that the blinds are already taken down?? I honestly don't know why I still order from them as I have to deal with problems with every order I place.