Consumer watchdog Which? has called on telecom companies to stop “unconscionable” plans to raise broadband and mobile prices in April.

Which? has written an open letter to major broadband and mobile providers, including BT, EE, O2, and PlusNet, urging them to stop any “unfair and unpredictable” price increases.

Telecom providers are expected to announce their plans after the next CPI inflation announcement on January 17.

Ofcom, the Government’s regulatory body, has proposed a ban on this practice, citing “substantial consumer harm” that it could cause.

Which? has said that customers face a “lose-lose choice” between increases that could leave them struggling or facing exit fees, putting them at the “mercy” of providers.

Providers are expected to generate more than £400 million through price increases in April.

Director of policy and advocacy at Which?, Rocio Concha, said: “Millions of people face price rises they could never have predicted when they signed broadband or mobile contracts and may struggle to afford.

“Given the regulator has found inflation-linked, mid-contract price rises harm consumers and set out proposals to ban them, it would be unconscionable for telecoms providers to proceed with these hikes.”

Many customers experienced a monthly bill increase of up to 17% last year.

Rocio Concha added: “Telecoms firms must do the right thing – scrap their plans for unfair price hikes this April and end unpredictable, in-contract, price increases once and for all, so everyone can understand what they will pay when they sign up to a contract for these essential services.”

CEO of Zen Internet, Richard Tang, said: “Broadband companies have been tricking customers for years by advertising one price, but then hiking that price mid-contract in a way that customers don’t understand.

“But, despite the ongoing cost-of-living challenges, consumers still face increases this spring before the proposal can come into effect.

“Our industry has a poor reputation for managing customer expectations and being transparent with communications. It is time for this to stop and for providers to give consumers much greater clarity and certainty over what they will pay for their broadband services.”

Chancellor Jeremy Hunt recently promised to write to the Competition and Markets Authority (CMA) after financial journalist Martin Lewis challenged him to prevent mid-April contract increases.

Mr Lewis argued that “baking in above-inflation rises is terrible for consumers”.

Mr Hunt said: “If you write to me with the evidence that you’ve got of that, evidence from your viewers, let me write to the Competition and Markets Authority who are the body that look into these things independently of politicians, let’s get to the bottom of it.”

Which? And Mr Lewis are now expected to submit a letter to Mr Hunt in the next seven days.