Being a gadget fan can be expensive, with high-end mobile phone contracts that can cost over £40 a month. But what you might not know is you could be paying well over the odds for your mobile phone bill.

New research shows that three major mobile network providers don’t cut bills when users have paid off their handset. Vodafone, EE and Three customers could pay as much as £38 extra monthly if they stick with the same phone at the end of their contract.

So are you paying too much for your mobile phone bill? Could you cut the costs? We’ll take you through what you need to know.

Why you could be paying too much

The research from Citizens Advice shows that customers of Vodafone, EE and Three keep paying the same for mobile phone bills – even after they’ve paid for the handset. On average, customers spend an extra £22 a month on a phone they’ve already paid for.

When you sign up for a mobile phone contract for 18 months or two years, your monthly mobile phone bill includes the cost of your handset. Then, over the length of your contract, you’ll pay this off.

If you’re still happy with the phone, you might decide not to upgrade at the end of your contract. Instead, you can just stick with your old handset.

But if you do this, you should pay less for your monthly bill. This is because you’ve now paid for your handset – your mobile phone bill is now just for your minutes, texts and data.

The research showed that 36% of people with a mobile phone contract kept the same phone after the end of their fixed-term contract. This means they might have still been paying the higher price for their mobile phone bill – even though it should have been lower.

Cut the cost of your mobile phone bill

If your mobile phone handset is still in good nick and you want to keep using it after your fixed-term contract ends, make sure you’re not paying too much. You can go onto a SIM only deal – this should be cheaper than your old contract.

Your mobile phone provider will usually contact you when you get near the end of your contract. They should offer you a new SIM only deal. If they don’t, make sure you give them a call to ask for a cheaper mobile phone bill.

But you don’t have to stay with your current provider – you can switch to another mobile network. Your existing network provider will have to unlock your phone for you to be able to do this. If you’re out of your fixed-term contract, this should be free. You can then use a price comparison site like uSwitch to compare SIM only deals from as little as £4 a month.

One thing to look out for is that the cheapest deal might not necessarily be right for you. If it doesn’t give you enough minutes, texts or data for your needs, you might end up going over your allowance. And if you do this every month, it could work out pretty costly.