Tim Lamb wrote:

my Vodafone service is suddenly very intermittent

Stick your postcode into

https://www.vodafone.co.uk/network/status-checker

If I guessed right, it told me for 2G, 3G and 4G

We're aware of some network issues in $POSTCODE

Theres a problem with our mobile network in this area at the moment
that may be causing issues with your service. Were sorry if youre
experiencing any disruption, we know how frustrating this can be.
Unfortunately, its taking us a little longer than we expected to fix
this issue €“ sorry for the delay. Rest assured, well get things up and
running again as soon as we can, and well update this page once we have
an update. Thanks for your patience. As soon as we have any further
updates, well let you know here.