Which? has launched a new Fixed Means Fixed campaign to try and put and end to cost increases that occur on supposedly locked mobile phone contracts.
An investigation from the firm found that 70 per cent of people on fixed mobile contracts were not aware that companies could increase prices.
This scheme has been launched as Three Mobile becomes the latest provider to increase its prices to existing customers. They are due to rise by 3.6 per cent.
The company has claimed that mobile firms are making up to £90 million a year by legally using these hidden contract clauses.
Executive director of Which? Richard Lloyd said people are often left "trapped" in a contract, meaning they won't be able to switch provider without paying a large penalty.
"Ofcom must intervene now and stamp this out. Consumers must be confident that fixed really does mean fixed," the expert was quoted as saying.
Posted by Simon Thomas