Hi there everyone
Thanks to you all giving your opinions, I had to the courage to go back to Soak & Sleep to do battle. I mentioned that I had canvassed opinion on a forum, and that I was a good customer who has spent a lot of money with them. I also mentioned Trading Standards and that the item obviously wasn't 'fit for purpose', and they suddenly did an about face and instead of the 10% refund that had previously been offered, have now agreed to send me a replacement sheet. Hopefully this one will wear better than the first.
In answer to your question Nelliemoser, they're definitely marked 100% linen, and at £40 for one sheet which was a special offer at the time, they're normally £45, it wasn't exactly cheap, especially when you can get a good cotton percale flat sheet from Debenhams for £16.00.
Thanks once again for all your opinions and support.
Judi