Furniturebox's products are listed and sold via other marketplaces and third party retailers.
If you have purchased the product through one of these channels, you will need to raise any queries through that marketplace or via the third party retailer that you originally bought the product from.
In terms of third party retailers, the purchase contract you have is with them and they are responsible for resolving any query or issue you may have relating to your purchase with them.
Furniturebox Website: https://www.furniturebox.co.uk/