The Consumer Banking Australia report, released on the eve of Bendigo Bank’s 150th anniversary next week, showed customer satisfaction levels had dropped 4.3 per cent.

The biggest drop followed confirmation of Bendigo’s merger with the Adelaide Bank in November last year.

Although losing ground to some competitors, Bendigo Bank has an overall customer approval rating of 86.8 per cent.

Adelaide Bank had the second biggest drop in customer satisfaction levels, down 4 per cent over the year.

Bendigo Bank general manager marketing and corporate affairs, Owen Davies, said the bank was pleased to have maintained its ranking as the bank most popular among its customers.

"The Bendigo and Adelaide Bank remains focused on serving our customers to the best of our ability," Mr Davies said. "Ratings for the past decade have shown that a very high percentage of customers are happy with our service.

"In addition, we note the rating of Adelaide Bank has risen, which we believe is a positive reflection on the bank’s merger to form the Bendigo and Adelaide."

Mr Davies said rising interest rates were an underlying factor that had influenced customer satisfaction on a broader scale.

"We are mindful that over the past year Bendigo Bank’s rating has fallen, but we also note that the ratings of all banks but Adelaide Bank have dropped in the past month, which we believe reflects customer dissatisfaction with rising interest rates," he said.