Refunds are not refunds since they secretly expire

I purchased some goods for my wife's birthday in 2022, some items were somehow not in stock and I received a refund. I decided to keep the refund for the next birthday. When it got to the next birthday the refund was gone, Netflorist explained that the voucher expired. This happened in July/Aug and until today they just lift their hands up and nobody is resolving this.