I have a 4Gb SD card that failed in the camera and has some precious shots on it. I believe the controller is dead as nothing will see the card at all.

Has anyone used a specialist recovery company for SD cards..any recommendations?

DIY approach first:
Flick the write-protect switch on the card.
Try it in a number of different card readers – some cope better than others.
Check if the card manufacturer has recovery software on their website.
If not then get hold of SanDisk RescuePro and see if that helps (note: they give away licenses for this with some SanDisk cards)

PhotoRec is another good one. when you say nothing will see it? Does windows/ or your OS ask you to format it when you put it in? Does it show up in Disc Manager?

Thanks both but I’ve tried the card in Windows/MAC 2x different cameras and it is never picked up at all. I think the card controller has completely died.

Any luck in Linux? You might be able to dd the image into something recoverable…

Try Clonezilla / Norton Ghost 2003…

Have you got access to different (USB) card readers?
Some have more luck than others with bad cards.

Have a punt with Recuva. Awful name, good product.