Barclaycard paves the way for rate rises The lender's letter says: "Your current rate tracks the Bank of England Base Rate, however the new rate is set by Barclaycard and can vary from time to time." There is no explanation of why the change is being made, although the letters do point out the alteration comes "at a time when the Bank of England's Base Rate is at an all-time low." The Bank Rate plunged from 5.75pc in mid-2007 to 0.5pc in March 2009 where it has since remained. Barclaycard declined to say how many customers were implicated but told The Telegraph: "We are simplifying the way we calculate interest on some of our Platinum cards. These will move to a standard variable rate, which is how the vast majority of our interest rates are calculated. We wanted to ensure the best for our customers and so have chosen to introduce these changes at a time that will be most beneficial to them. The switch to the standard variable interest rates reflect our existing rates and the new rates are, in some cases, lower. Tracker rates on both credit cards and mortgages, agreed before the precipitous plunge in the Bank Rate, have become a nightmare for lenders who have sought to wriggle out of their "tracking" obligations wherever contracts permit. Bank of Ireland UK is the latest lender to become embroiled in this controversy: earlier this year it increased the "differential" by which the mortgages of almost 13,000 borrowers tracked the Base Rate. The Financial Ombudsman Service is currently considering whether this was fair. Barclaycard's move comes as rates on plastic are drifting up more widely. Moneyfacts, the data compiler, says average long-term card rates - aimed at mainstream borrowers - reached an all-time high in April this year, at 19.1pc. They have since dropped back fractionally to an average 18.9pc, Moneyfacts's Rachel Springall said, though the trend is "in the upward direction." But while rates are going up, card issuers are competing more aggressively to attract new customers - by offering either low, ongoing rates for those who want to manage balances down over the long term; or by offering extended 0pc deals. "Today, if you look at the best deals, you've either got a low borrowing rate with no added perks, or you've got a long interest-free period followed by a high revert rate," Ms Springall says. She cites Sainsbury's Bank's Cashback Low Rate card as an example of the former charging 7.8pc. An example of the interest-free offers is Tesco Personal Finance's deal charging 0pc for 18 months, followed by a revert rate of 16.9pc. Credit cards remain hugely popular and widely-used in Britain, although total borrowing on plastic has been reducing. The latest annual statistics from the UK Cards Association, the sector's trade body, published last month, said outstanding borrowing on credit cards "has fallen from a peak of £67.4bn in 2005 to £55.1bn at the end of 2012." This represents about 4pc of the country's total personal borrowing of £1.4trillion, it said. It added that 81pc of all credit and charge card spending in 2012 was made by cardholders who repaid the balance in full. Is your card rate rising? Tell us at money@telegraph.co.uk