Bodyline contact HELP! Mistake in order!

Hi hi, this is my first post on egl... I really thought it would be something more ~*majestic*~ than this for a first post, but of course an ordering mishap is my introduction... xD;;
Anyways, my name is Maria, I'm 17 and I live in Christchurch, New Zealand. My loli community is one of maybe 3 in this country, from what I've heard? We're little! There are around 8 or 9 lolitas that are in my community here. So not very big. I'd say half of us are long time lolitas and the other half just beginning. I've been a lolita for just over a year now... Been into it for a long time!

So to my question... I've ordered from Bodyline many times before, and never had a problem. I ordered a JSK from them a week ago and it just arrived this morning... I thought it unusually heavy when I brought it in, and when I looked at the packaging it had 'dress' listed twice on the contents list! I only ordered one dress and nothing else so I was confused... When I looked inside I discovered they actually sent me the same dress twice... Thankfully they only charged me for one!

But now I'm unsure of what to do. Obviously I need to tell them they sent me a free dress accidentally! I went to the website and to their contact page, but like last time I looked, the form's submit button isn't actually linked to anything, and their email isn't listed. Someone please help me figure out how to contact them? I'm sorry if this is an obvious question or breaking the rules somehow... I looked around and didn't find anything related. :c
update: thanks for all the comments you guys! my friend found on the website a part where it says they don't accept returns or exchanges, even in cases where they've made a mistake. because of this, i've decided to keep it. thank you all so much! you were all very helpful. <3