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What type of Payg tariff is he on ?
i.e Big value bundle = is there any data allowance left.
i.e Payg1 = is there any credit left on the account.
Check in myvodafone for any data bar.
Also check in the phone that no data cap has been activated if the phone has this feature.
Ask him to check on his phone that mobile data is still turned On.
And as a process of elimination can he try his sim card in another phone.
Also ask him to check his internet settings.
Text WEB to 40127 to get the settings.
Further help in 》 Set-up-your-phone-for-internet
To add it maybe worth checking his postcode in the status-checker just to ensure no mast issues exist.
Current Phone > Samsung Note 10+ 5G
Samsung One Ui 2.5 / Android 10.