Yeh, its something to do with the consumer credit act. The cc companies tend not to shout about it, but I seem to remember that you have protection if you spend £100 or more. Interestingly, if you spend only £101 on the credit card, and pay the £2899 balance cash, the cc company is liable for the £3000.
The law may well have changed, so check before relying on my words of wisdom.