I'm not sure why people think it's ok for upholstery fabric to fade
Any consumer rights post on AIBU always gets terrible advice. British people hate to complain.
Disappointed? Yes. Disgusted? No.
It's MN, OP is supposed to be incandecent with rage. People who have appropriate emotional reponses to everyday irritations post on Netmums instead.
am I being unreasonable to say that this is a fault with the fabric and it shouldn’t be used on a footstool if it isn’t colour fast?
No, you have a legal right to expect your purchases to be of appropriate quality, fit for purpose and to last a reasonable length of time. Send a 'letter before action' giving them chance to either fix it or refund you the cost of the stool. Never speak to them on the phone- do it in writing. If you have to go to small claims you will get the money back eventually and it's not hard, just slow.
This website may help: www.resolver.co.uk/
Alternatively there are many example letters before action online (a lot probably written to DFS).
look at so many used DFS sofas on ebay; nearly all look as if they've lost an argument with a herd of elephants
I'm always puzzled that they are still going. Surely if you've heard of them it will be a horror story and if you haven't heard of them you'd at least google?