I've used the Lighting Superstore in the past, and it's been okay. However, this practice of taking the money from your credit card is poor one, but threatening them with action for theft won't work, since a business will always fall back on the defence that they had no intention of permanently depriving you of your goods, which is the legal definition of theft. Far better to go to your credit card issuer and demand restitution under section 75 of the consumer credit act.
This, of course, only applies if you've paid by credit card; you should never, ever pay for anything over £100 on anything but your credit card, naturally, since credit cards offer extensive consumer protection.