I had mine done at TF Tuned, back in three days and cost about 85 quid. and I believe the Specialized Concept Stores can arrange it too.
Also, if you have a look on mtbr.com, there is a thread in the Specialized forum by a bloke called Kelstr who gives a step by step servicing guide for the e150 forks and the shock – if you're handy with spanner (I'm not).
There's also a thread on there about replacement shocks for the SL – it's a U.S website so the Manitou Evolver ISX-6 is highly rated but I can't seem to find much about it over here for servicing etc. Plus it £500 notes 😯
http://www.chainreactioncycles.com/Models.aspx?ModelID=21366