Terrible service at Zando

Bought a very expensive duvet cover (Linen House) from Zando. One of the pillowslips lost colour after washing. Sent them photos and they decided that I used a chemical substance on the pillowslip. I expained that if I did use a chemical on the pillowslip,why is only the back of the pillowslip affected and the front is perfect. Talked to Coswill and he just adamently stated that they would not refund me or exchange the cover. I won't be buying from Zando ever again. Beware they find a reason to make it the client's fault. Duvet cover 3 months old.