Welcome to Vodafone Community
Have you been able to set up your myvodafone online version @NicolaWright
Is this a new Vodafone payg account or have you just swapped to a new phone ?
Or have you ported from another network to Vodafone Payg ?
Live Chat or the Vodafone Social Media Teams via Contact-us-for-account-specific-queries can help.
Just to add ensure wifi is off and any Vpn removed.
On android go into something similar to settings , apps, myvodafone, location, delete data and cache
Try deleting the app and delete it from any relevant app store library.
Current Phone > Samsung Note 10+ 5G _256Gb > Model: SM-N976B.
Samsung One Ui 2.1 / Android 10.
Samsung Gear s3 Frontier Watch.
Samsung Galaxy Buds.