It is thought that criminals are buying certain numbers, setting them as premium contacts and then hacking into phones.
Victims of this newest scam are being hit with £300 phone bills, for being connected to these numbers for up to 12 hours, for numbers beginning with either 0845 or 0843.
It is not yet clear how people are hit, as customers have been reporting these charges whether they answer, ignore or call the number back the investigation by Money Mail found.
It was only discovered after customers complained about the large bills they were receiving, saying they had not phoned these numbers.
Ofcom has confirmed that this is an industry wide problem and not confined to a specific network.
Vodafone customer Ruth Dance, from Bracknell in Berkshire, was billed for £300 after being called from 0843 9800 146. Her network provider, Vodafone, insisted that Ruth must have made the phonecall, which lasted over nine hours. When Money Mail called the number, it connected to the voicemail of a firm called Money Help Marketing.
Another customer, Diana Dentith, from Lowestoft. said that her usual monthly bill of £9 rose to £375 after she missed a call from 0845 429 0015.
Also a Vodafone customer, Diana said that she was originally told that she must have called the number for 12 hours.
The firm told ITV News it has now reimbursed ‘anyone that we know about’ and said that customers who fear they have been targeted should call the company on 191.
Vodafone also said they were working with regulator Ofcom and other mobile operators ‘to identify and close down this issue as soon as possible.’
In a statement, they said: “We have taken proactive measures to ensure none of our customers affected are out of pocket, and we have identified and blocked the numbers related to the fraud.”
Telecommunications expert Ben Levitan said: “There are people who spend their lives looking at phone companies’ systems and ways to make money from them.
“People share these secrets online and use them, but the criminals can be very hard to trace and catch.”
Ofcom said it is “very concerned” by the scam and said it is working with industry experts and mobile operators.