Operators of ATM fleets have clawed back more than A$5 million a month in fees charged to users of machines that charge for using the "wrong" ATM - that is one not part of the fee-free network operated or affiliated with the customer's bank.Monthly data on the use of automatic teller machines published by the Reserve Bank of Australia shows that the proportion of cash withdrawals at ATMs owned by an institution different to that of the cardholder was 41.1 per cent in February 2012.This is the highest proportion since the shift to the new model for charging ATM fees came into force in March 2009.Prior to that change around 47 per cent of ATM withdrawals were made at the "wrong" ATM. This dropped to a little less than 40 per cent once the new fees - these were prominently displayed at ATMs - came into force. The percentage fell to as low of 37.3 per cent in April 2011, with the fall possibly explained by the general caution in discretionary spending by all households.ATM operators are also experiencing a revival, albeit modest, in the growth in the number of transactions. Transaction numbers fell over most of 2010 and during the first half of 2011. Growth, on a 12-month basis, re-emerged in the third quarter of last year.Consolidation is underway in the ATM sector with EzeATM taking over the fleet operated by iCash Payments, while DirectCash (from Canada) seeks shareholder approval for a take-over of Customers Limited.