The big banks have steadily improved their retail customer satisfaction ratings over the past decade, but they have failed to convince one key segment - their high value customers.Roy Morgan Research has included a breakdown of customer satisfaction by footings (the value of the business the customer has with their bank) in its latest consumer banking customer satisfaction report. It found that customers in the highest quintile, who account for 65 per cent of total footings, give lower ratings than other customers.Commonwealth Bank has an overall satisfaction score of 80.4 per cent, which drops to 75.4 per cent for customers in the highest quintile.For National Australia Bank, the corresponding scores are 79.3 per cent and 72.3 per cent, respectively; for ANZ they are 77.3 per cent and 72.1 per cent; and for Westpac they are 77.1 per cent and 73 per cent.Roy Morgan Research's industry communications director, Norman Morris, said: "All of the major banks achieve their highest satisfaction levels among their lowest value customers."The challenge now is to lift the satisfaction of high value customers and potential customers if profit is to be impacted."Morris said there were two areas where the big banks scored poorly with their high-end customers: the latter want their banks to be more flexible in meeting their needs; and they are critical of the level of fees and charges.Banks that score well with high-end customers include Bendigo and Adelaide Bank, which received a rating of 87.7 from top quintile customers, ING Direct (also 87.7 per cent), Suncorp Bank (84.5 per cent), Bank of Queensland (83.1 per cent), Macquarie Bank (82.8 per cent), Bankwest (82.5 per cent) and St George Bank (79.5 per cent).