Yes you can swap from pay monthly to pay as you go @Miren.
First get a pay as you go sim card (try and find a classic one, perhaps on eBay).
Once that arrives, call customer services and ask them to move your number to the PAYG sim.
To keep your sim active, you will need to have a chargeable activity (calling, sending a text or using data) once every 6 months and topping up every 999 days.
Please note, this is not customer services and we cannot access your account. Do not publish personal details (email, phone number, bank account).
Link to our guide on how to contact them can be found here
