You have to remember that when you send orders for things like flowers overseas, you are at the mercy of the florist local to the recipient.
Even in this country things can go wrong if ordering online, as I found when I ordered flowers to an aunt's 90th birthday. They sent the flowers and apparently were very nice but put no card in with them and refused to tell my aunt who had sent them !
At least you have a photo as proof, so get a refund from the company that your order went via as the contract was with them. They can then be responsible for the Croatian end.
Perhaps send flowers later - on the anniversary of their death or on their birthday perhaps.
Anger management!!! Help needed.