American Express Australia has reported an increase in net profit for the year to December. However, documents lodged with the Australian Securities and Investments Commission show that the underlying business has weakened.Amex's revenue last year was $1.06 billion - down 7.6 per cent on the previous year.The value of card member receivables and consumer loans fell 6.9 per cent, from $4.3 billion to $4 billion. Charge card receivables, credit card receivables and consumer loans were all down.The improvement in the bottom line was the result of cost cutting.After cutting salaries and "intercompany staff charges" by 8.5 per cent, marketing and advertising expenses by 9.5 per cent, and general administrative expenses by 7.8 per cent, Amex increased its net profit from $8.5 million to $13.6 million.There was a big improvement in the charge for bad and doubtful debts, which fell from $76.4 million to $54.1 million.No one at the company was available for comment.