I was in the Nike factory last Saturday and bought...

I was in the Nike factory last Saturday and bought a lot of things.
When I got home I discovered that one training t shirt was size Small I use size Xl / XXL.
On the hanger there are small signs and it said XL. So I bought it in good faith. Today Wednesday I went out to the Nike factory again and had unfortunately lost the receipt, which is of course regrettable.
I asked nicely if I could swap it as I can in no way use it. Same t shirt just for the right size and was greeted by a young clerk then said it was just annoying, incredibly flabby.
Of course, it's a shame I do not have the receipt anymore as my boyfriend has thrown it out. But honestly I'm not asking for money back! The brand, etc. Deter still on. This is the last time you spend DKK 2,000 on you.
-3 in customer service.