Ed Miliband has called for an end to Britain's "rip-off consumer culture", insisting the government should intervene on exorbitant charges for savings, holidays, banking and parking.
The Labour leader urged David Cameron to take a tougher approach to "predatory" companies that exploited customers.
Speaking to the Daily Telegraph, he proposed the creation of a new consumer watchdog to limit pension fees, car parking charges and airline levies.
The comments come amid growing concern that families are being exploited by irresponsible companies at a time when they are struggling to cope with rising prices and austerity measures.
Mr Miliband said: "In every area, you have to call time on the surcharge culture.
"Making a fair profit is important but it can't be done in an underhand and predatory way.
"This is about power in relation to private services and how government can be on the consumer's side. Lots of businesses recognise this. It's part of how you build a competitive economy in the world."
He added: "It's about the rules that government sets. This is a specific argument about a number of private services to the public. (For example) we're not proposing to go back on taking the railways into private ownership but maybe in transition not enough was done to protect the public."
Mr Miliband said the plans would ultimately help business to become more competitive and points to America, where consumer regulation is tougher.
"People's living standards are squeezed as never before, and we have to do everything we can to relieve that burden," he said.
The Labour leader identified several areas for immediate action, including:
- Savings fees: pension firms should set out how much they are charging savers to invest, after research showed that up to 16 fees and levies can be applied to private schemes. If charges do not fall, total charges should be capped;
- Car parking charges: the cost of parking at railway stations has increased dramatically, with Southeastern trains recently raising prices by 16%. Prices should be capped, along with season tickets and other fares;
- Airline levies: travellers face a range of charges for baggage, paying with a credit card and even checking in without printing out a boarding pass;
- Bank charges: banks make £2 billion annually from unauthorised overdraft fees. A new watchdog should have the power to intervene and outlaw excessive fees;
- Consumer helplines: it is unacceptable that people are charged "50p a minute just to complain";
- Energy companies: the big energy firms should be broken up and transparent pricing introduced to enable proper competition.
- Mr Miliband said he was ridiculed when he warned of the dangers of "predatory" capitalism in a speech last year, but his approach had since been adopted by the Coalition.