Stradivarius Order Marked "Delivered" But Courier Says It Was Returned

I placed an order for a buttoned vest and pants set from Stradivarius on June 27th. My order shows as delivered through the courier company Kolay Gelsin, but even though days have passed, I never received the product. On Stradivarius's website, my order shows as "delivered," but when I called Kolay Gelsin, I was told the product had been returned.
I never created any return code, and I don't understand how the product could have been returned without ever reaching me, without my approval or knowledge. What's more, I couldn't find any channel to contact Stradivarius directly, and I also couldn't find any live representative to speak with at Kolay Gelsin — I only receive an automated message saying "your product has been returned." My order tracking number is 201812112.
I am requesting that my product be sent to me again urgently. I also expect a gift or gesture as an apology for this hardship and the lack of communication I've experienced.