Hi --- Try your local trading standards or CAB, under the sale of goods act certain items are expected to last even up to a lengthy period of Six years as being fit for their purpose without becoming defective.
That cannot be dismissed as general fair wear & tear or be seen as acceptable, otherwise every leather suite sold in the Country would only have a life expectancy of just under one year. !!!
It would be perfectly reasonable to expect a new leather suite to last a lot longer than a year, before showing the problems such as you're experiencing, particularly as you have an additional warranty --- (which does not affect your statutory rights).
Insist on your statutory rights by getting the item replaced, repaired or refunded under the sale of goods act, then demand back your £200 warranty money as it has been proven that it was of "no benefit" when there was a valid claim made under the warranty.