The Big Four have taken another hit to their customer satisfaction ratings, with business customers joining consumer banking customers in marking them down.According to the latest DBM Consultants Business Financial Services Monitor, business customers gave all but Commonwealth Bank a lower rating in March.DBM said the drop was due mainly to dissatisfaction among micro businesses, which gave all the big banks lower scores last month.Last week Roy Morgan Research reported that consumer banking customer satisfaction with the Big Four had fallen steadily over the past three months.Roy Morgan said the fall was likely due to the impact of the debate about bank conduct and also the banks' move to raise mortgage rates late last year.DBM attributed the fall in its survey to the media focus on bank conduct."Even when businesses are receiving good service it is not always possible to put the adverse publicity to the back of their mind," DBM director Maria Claridad said in a media statement.DBM said that overall, CBA had a satisfaction rating of 7.4, National Australia Bank 7.3, Westpac 7.2 and ANZ 7.1.Companies with revenue of A$50 million or more gave the banks higher ratings in March. Businesses in this group are the most satisfied, giving CBA and NAB a score of 7.8, ANZ 7.4 and Westpac 7.3.