A RBS spokesperson said: "We know we can do more to improve the experience for customers in certain aspects of our service.
"We’re investing in dedicated teams focussed on making targeted improvements for customers and rolling out continuous changes to make banking easier, such as our software to help reduce queuing times in branches and expanding our AI technology, Cora, through the introduction of voice banking."
Consumers were least likely to recommend TSB for its online and mobile banking services, with the bank achieving a score of 63 per cent.
The survey results were collected between July 2018 and June 2019, a period which followed closely on from IT failings at TSB in April last year which saw almost two million people locked out of their online banking services.
A TSB spokesperson said: "The CMA data highlights areas where we offer strong customer service as well as some specific areas where we need to continue to improve.
"Improving customer service in all areas of our banking offer is a priority for us over the coming months."
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