I've just tried Vanish PowerPowder and it's brilliant.

[StellaAndFries]

This stuff here. Its turned my carpet back to its original colour, it's only been down a year and has been regularly shampooed but I didn't realise quite how dull and grubby it was until using this. It smells lovely too and for about £5 isn't too expensive.

Does it work like shake and vac used to?

It freshens like shake and vac but actually cleans too. You shake it like shake and vac and then brush it in, leave it for 20 minutes (well I did school run so more like 40!) and then Hoover off. It is really quite strong smelling though so I don't think you could stay in the room for the 20 minutes unless you have the windows open. I moved the sofa earlier and now there isn't a difference in shade from where the carpet has been used and where it hasn't.