I've had it since a free balance transfer offer last year and haven't used it since. Then, out of the blue last month, a letter saying I'll receive 3% back on all spending until 31st January. I pay off the balance every month, so no idea of the interest charges. Although it's not the best cashback offer, I didn't have to apply for a new card.
You could try RBS and see it the promotion is still on (01268 508023).
DK, To add to FB's answer, you can place only one £3k in a cash mini-ISA (as you did 6 years ago), but you can place another £4k in a stocks and shares mini-ISA. There is a risk that the shares can go down as well as up. (Nor necessarily a good idea though if you intend to take out the money within a few months/year.) I found some information here: http://www.moneyextra.com/guides/individual-savings-accounts-011457.html#N100BE with which I have no connection.