Retail customer satisfaction with the big banks plateaued towards the end of last year and has been falling since the start of the year.According to the latest Roy Morgan Research consumer banking customer satisfaction report, ANZ, Commonwealth Bank and Westpac lost ground in February, compared with the previous month, and all four of the big banks suffered falls in their satisfaction over the six months to February.Roy Morgan industry communications director Norman Morris identified out-of-cycle mortgage interest rate increases announced by the banks last October as the main cause of negative sentiment."Satisfaction levels for home loan customers of the Big Four are below the levels seen prior to the rate increases," Morris said.Among the big banks, Commonwealth Bank had the highest level of customer satisfaction in February, with a rating of 82 per cent, followed by National Australia bank (80.5 per cent), Westpac (79.8 per cent) and ANZ (77.9 per cent).Among the other institutions in the survey, Beyond Bank's rating was 95.4 per cent, Teachers Mutual Bank's was 95.3 per cent and Newcastle Permanent Building Society's was 94.5 per cent.Citibank had the lowest rating in the survey, with 71.7 per cent of customers saying they were satisfied with the bank.