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Was your Internet cut off for non payment ? If so it may take a short time to be re activated. Ask customer services on 191 or Live Chat to check your account.
Other things to check are ;
Is mobile data still turned On in your phone.
Is this happening everywhere ? If not then it could be a mast issue.
If your using an android phone check any relevant data level usage settings.
Check your myvodafone for any relevant data bar toggles.
Try turning your phone Off and On.
Is there any data icons showing in your phone's status bar such as 4G or 3G etc ?
As a process of elimination can you try your sim card in another phone.
Vodafone have a help thread including a template here Network-issues-initial-checks-and-template.
Current Phone > Samsung Note 20 5G - SM9860 Snapdragon.
Samsung One Ui 2.5 / Android 10.
You don't mention the device you are using.
Assuming this is a phone and your calls and texts are working this won't be a billing issue. It's more than likely your SIM has temporarily lost it's connection to the network, try updating your SIM on the network, this is done by going into your connection settings, select mobile neworks, network operators, select manually and let your phone search for available networks, select any other network, when it rejects the request reselect Vodafone. Follow this with a reboot.
If you still have issues speak to Vodafone through the customer service channels and an advisor will help.