The UK competition watchdog has reviewed cloud storage services used by millions to store family photos, films and music.
The UK competition authority has ordered a shake-up of "cloud storage" services used by millions of Britons to store family photos, films and music via smartphones and tablets.
It found that unfair terms in some contracts could mean people losing access to content or facing unexpected charges.
The Competition and Markets Authority (CMA) said that following its review of the sector, providers Dixons Carphone, JustCloud and Livedrive had committed to fairer terms for customers.
It said it was "continuing to work with a number of other companies" to make their terms and practices fairer and expected them to make similar improvements - warning that those that did not comply with consumer law risked enforcement action.
Nisha Arora, CMA senior director for consumers, said: "Cloud storage offers a convenient means of keeping family photos, favourite music and films and important documents safe, and accessing them quickly from any device.
"Our review found that people find these services really valuable.
"However, we also heard some complaints resulting from unfair terms in contracts.
"If left unchanged, these terms could result in people losing access to their treasured possessions or facing unexpected charges."
Cloud storage enables users of devices such as smartphones and tablets to store data such as music, films and photographs on remote servers.
The CMA said around three in ten British adults currently use cloud storage in a personal capacity.
A review of the sector heard concerns that some terms and practices in the industry could breach consumer law.
These included companies having the ability to change the service or terms without notice, being able to terminate a contract without notice for any reason, or automatically renewing a contract without notice.
The CMA has also published an open letter to companies, advising to review their terms and ensure that customers were given the right information.
Meanwhile, it advises consumers to check that services meet their needs before they buy, keep an eye out for changes, and challenge contract terms they think are unfair.