Generally, the only way to guarantee you’re not penalised for cancelling a contract is to cancel within the cooling-off period.
Otherwise, if you cancel before the minimum contract term is up, you may have to pay an early termination fee. This can be very high.
For example, if you sign up to an 18 month contract and want to cancel in the second month, you may have to pay 16 months' worth of fees.
But you may be able to avoid these fees if you want to cancel your contract as a result of changes made by your operator.
For example, if your contract allows your operator to increase your contract by more than the Retail Price Index (RPI), you could challenge this clause as unfair.
Rules set by the regulator Ofcom mean that customers can leave mobile, landline or broadband contracts penalty-free if a provider ups prices mid-contract if the rise is of 'material detriment', for example a rise that's bigger than the RPI rate.
You can cancel your contract and switch to any other provider, as long as you do so within 30 days of receiving your price-hike letter.
But if your mobile phone provider has warned you about rises in their terms and conditions and they are in line with RPI, you won’t be able to leave if you’re still locked into a contract. If you do want to leave, you'll have to pay an exit fee.
If you’re outside the minimum term of your contract then you’ll be allowed to leave without paying. You should check with your provider about how much notice you need to give to do this.
Your mobile phone provider may be able to hike the price of your fixed contract by the rate of the Retail Price Index (RPI).