Epic game error!

Yesterday I bought some zp,and I opened some crates, in order to have coupons.I bought 30 rpk gold crates,and 35 of Ak scope.No win :S But I reached 81 coupons,so i went to Owned coupons,i typed in D.E. GOLD ( I'm 100% SURE !!), i already have m4a1 crystal,moreover.I go in storage and i have AK KNIFE!??!!!I'm 100% SURE I typed in D.E. GOLD ,NOT STUPID AK KNIFE.

I haven't obviously proof to demonstrate this,but i payed a lot of euros to reach a gun THAT I DON'T WANT??!!

Can I have the coupons or back or exchange gun?what can i do?I don't want ak knife, i already have almost all ak, please tell me how i can reverse this thing ,i'll do all in my chance.

sorry for my bad english.

GuEsS