Firms will have more time to resolve complaints, but can’t charge customers premium rates for phone calls.

The measures are a response to a review by the FCA around competition in the savings account market, which is worth £700m.

Under the new rules, providers must also alert consumers to changes in interest rates, for example when an introductory rate – often used to attract new customers – comes to an end.

The FCA will also require firms to report the number of all complaints received, including those handled by the close of three business days and to publish this information.

However, under the new rules firms will have to send all complainants a template letter telling them that if they are unhappy with the complaint resolution they can apply to the Financial Ombudsman Service.

Rachel Springall, a finance expert at Moneyfacts.co.uk, said: “Moving a savings pot from one bonus rate account to the next is a clever way to take advantage of higher returns, but for consumers who are less proactive, it may mean that they end up sitting on a paltry rate for a long time”.

The rules about complaints handling and reporting come into force on June 30, 2016, whereas the new rules for call charges will be implemented from October 26, 2015.

According to Moneyfacts, the average Isa rate on the market has fallen to 1.45%, down from 1.57% a year ago.

Christopher Woolard, FCA director of strategy and competition, said: ‘Our rules will help deliver the quicker, easier and fairer resolution to complaints that consumers want.

“When they wish to move accounts, they should be able to do so with the minimum of fuss”.

In January 2015 the regulator published the final findings of its savings market study, in which it found that banks and building societies “need to improve the transparency of their practices, with little information now being given to consumers about alternative products”.

Richard Lloyd, executive director of consumer group Which?, described the plans as “a significant win for savers”.

The FCA also intends to become active in publishing information to highlight which providers are paying poor interest rates to longstanding customers, in the hope that it will encourage those people to shop around and get a better deal. Online or mobile banking could be used to provide simple switching processes for customers.

[Related story: The bank accounts we’re dumping and where we’re switching].