http://www.ukclimbing.com/forums/t.php?t=628405&
According to the first post in the thread linked above, Wild Country won't replace slings any more. The only way to get new slings sewn on would be to send them abroad, probably to the U.S.
In reply to fmck:
That isn't shrink wrap tubing in Chris Tan's photos, it's tubular nylon tape. The same stuff people used to use to tie their own slings - available off the reel by the meter at any decent climbing shop.