By Jim Reed
Newsbeat technology reporter
Promotional offers that use words like "free" will be banned
Ringtone companies that trap customers in expensive subscription deals could be shut down overnight under new emergency rules.
The premium-rate phone watchdog says that complaints about mobile services like ringtones and text news alerts have more than doubled over the last year to 1,600 a month.
George Kidd from the watchdog, PhonePayPlus, told Newsbeat: "People are telling us they're getting ripped off and we've got to take that seriously.
"Some firms are starting to cut the corners. They hide charges, mislead customers about pricing and drop important details down into the small print. It's a tough market but that's not a reason for ripping people off."
PhonePayPlus said it has seen evidence that some customers have been charged thousands of pounds as a result of bad practice by some ringtone companies.
Many have tried to buy a single download and been signed up to an expensive subscription service without asking for it.
Radio 1 listener Rob Allen has been blacklisted by his mobile phone provider after refusing to pay a surprise £120 bill.
I bought one ringtone and then got bombarded with messages from the website I bought it from
Radio 1 listener
"I bought one ringtone and then got bombarded with messages from the website I bought it from," he said.
"It wasn't until the next bill came through that I realised I was being charged £1.50 a message.
"It didn't say subscription, it didn't say on the message that I was even being charged. I just kept deleting them without thinking."
PhonePayPlus said it now plans to force companies to display clearer pricing for premium rate content like ringtones.
It will use emergency powers to shut down services that trap customers in expensive subscription deals without making it easy to stop receiving ringtones or other content.
Other rules coming in later this year will ban promotional offers that use words like "free" and "cut price" without making clear the full cost of the service.
Companies will have to make the terms and conditions of subscriptions more obvious and customers will have to reply with a text message to opt-in to the deal.
Mr Kidd said: "If you want to join a subscription service then it's got to be presented to you in very stark terms and you have to respond with a text saying, 'Yes, I want to join'.
Responsible companies are crying out for action to remove organisations employing questionable marketing practices
The Premium Rate Association
"Giving out your number is not enough, they've got to present the deal to you, and you've got to say you want it."
The Premium Rate Association, which speaks for ringtone companies, said it welcomed the new proposals.
Its boss, Suzanne Gillies, said: "The many responsible companies in the industry are crying out for action to remove the small minority of organisations employing questionable marketing practices."