I wasnt entirely happy with my answer so had a look at their website...
For starters, you can buy their furniture off the web so they obviously have a delivery network. So, Id have thought you actually stand a good chance of asking them to direct a man in a van to pick up your furniture.
Secondly, if they resist utilising a network they already have in place, point out that you hiring a van to bring the furniture back will be a consequential loss of their furniture a) not being fit for purpose and b) of inadequate quality. As this is in contravention of the Sale of Goods Act 1979 Id have thought you could pursue this legally.
Good luck!