Rather than fork out another £75 on flowers and risk it happening again why not transfer some money to your friends family in Croatia and ask them to place flowers on the grave for you, alternatively let them donate the money to a chosen charity?
Tips on keeping the house cool in very hot weather
Favourite small treat when feeling blue or conversely a bit flush


The son sounds lovely, making contact with you in that way. I’d do as others suggest and explain the situation then, if you get a refund, offer to donate it to a charity of his/his mother’s choice. 