The debate about bank behaviour has taken its toll on customers' attitudes towards their financial services providers, particularly the Big Four.According to the latest Roy Morgan Research consumer banking customer satisfaction survey, the average satisfaction level of the big banks has fallen steadily over the past three months - from 80.9 per cent in December to 80 per cent in March.The whole banking sector has taken a hit over that period, with the total bank average falling from 82.8 per cent to 82 per cent.While satisfaction with the Big Four remains close to historical highs, it appears to have peaked. The big bank that has suffered the biggest fall over the three months is Commonwealth Bank, with a fall of 1.1 percentage points.However, CBA continues to have the highest rating among the big banks, with a score of 81.3 per cent, followed by National Australia Bank (79.9 per cent), Westpac (79.4 per cent) and ANZ (78 per cent).Roy Morgan industry communications director Norman Morris said the satisfaction of home loan customers was below that of other bank customers, suggesting that the out-of-cycle rate increases in October and November last year were another factor contributing to lower satisfaction levels.