Why am I paying almost twice as much on o2 when other providers are cheaper?

[Vic6]

Why am I paying so much for my sim only, when other providers are cheaper. My partner pays half the price with BT. 

[Bambino]

@Vic6 I guess it depends on how long ago you agreed to the tariff you're on. If you think you can do better elsewhere and want to keep your number, see this guide: Cancelling your contract - An updated guide - O2 Community

Edit: If you're happy with the phone you have, shop around: SIM Only Deals: Compare our best in June 2024 - Uswitch