More than 13 million mobile and broadband customers could see their bills rise by £100 next year due to inflation-busting price hikes, Citizens Advice has warned.
The charity has found nine out of 10 broadband customers and seven out of 10 mobile customers are with providers who can hike prices halfway through a contract.
Many providers are set to increase prices up to 3.9% beyond inflation.
Citizens Advice warned that with recent estimates putting inflation at 12.6% in January, mid-contract price hikes will be much higher this year than in previous years, at a time when people are least able to manage them.
It found that one in three mobile and broadband customers facing price hikes has already cut back on everyday essentials such as food, energy and clothing.
It is calling for providers to axe the price rises, which it predicts could cost consumers £2.5 billion more next year.
The charity warned that access to mobile and broadband internet must remain affordable as most people rely on them for employment, managing benefits and staying in touch with loved ones.
It found that more than a third of broadband and mobile customers facing price rises are already worried about being able to afford the services at current costs.
Across both markets, one in four customers did not know their prices could go up mid-contract, and a further two in five were aware they could rise but did not know by how much.
Citizens Advice chief executive Dame Clare Moriarty said: “Every day our advisers hear from people barely making ends meet as they try to cope with inflation and soaring household bills.
“As we all pull together in the midst of a cost-of-living crisis, mobile and broadband providers should be finding every way possible to help people.
“We want to see them cancel mid-contract price rises this year. Ofcom and the Government should then look to protect consumers from future ones.”