Halifax credit card - Charges you extra

As a first recommendation, don't ever get a Halifax credit card. They've just ripped me off for £74.70, when I mistakenly underpaid my monthly bill by 10p. I have tried explaining via telephone, but the usurious company will only offer me a £30 refund. Not a bad return - £44.70 for 10p. I've since written to the Halifax to explain that they can say goodbye to my custom for good.