Balances accruing interest on credit cards have fallen to their lowest level in six years, as consumers continue to turn away from high-rate cards as a source of personal finance.According to the latest Reserve Bank credit and charge card data, balances accruing interest on credit and charge cards fell 0.3 per cent month-on-month to A$32.1 billion in August.The average balance accruing interest was $1990.The last time balances accruing interest were lower was in May 2009.Consumers are continuing to use their credit cards for spending but they are not allowing balances to build up. They made 185.9 million purchases worth $24.4 billion on credit and charge cards in August.Consumers made 364.2 million purchases worth $19.8 billion on their debit cards in August.Credit card spending (by value) grew by 9.1 per cent over the 12 months to August, while debit card spending grew by 9.5 per cent over the same period.