Telecoms regulator Ofcom today indicated it could soon stop mobile phone operators from overcharging customers for handsets they have already paid off.
Millions of customers pay for their phone on a "bundle" deal which allows them to pay for the handset over a number of months.
Though many operators reduce the monthly payment customers make after their contract is up and they have paid off their handset, around 1.5m people end up paying for a phone they already own.
Ofcom described this as "unacceptable" and said operators should be more transparent with consumers about phone charges.
The regulator is now consulting on changes to make the industry fairer for consumers. Ofcom said consumers should be notified when they had finished paying for the phone itself, although some operators such as O2 already do this.
It also said it could force operators to put consumers on a cheaper tariff after they had paid their handset off, or notify them of alternative SIM-only deals.
It follows a Citizens Advice report earlier this month which found UK consumers were overpaying by £500m on phones they already owned. In particular, Citizens Advice picked put EE, Three and Vodafone as operators who were not treating customers fairly.
Lindsey Fussell, Ofcom consumer group director, said:
Mobile customers should get the best possible deal. We’re concerned that people are not told, or cannot tell, exactly what they are paying for.
So we are extending our work on behalf of mobile customers to ensure that handset charges are clear and fair – not just when they enter a contract, but also when their minimum period is up.