Hi R Baldock and welcome to the Vodafone eForum.
The message you are getting is from the VMC software not the network. You can set your monthly allocation, via a
usage meter, and it tracks it for you, and warns if you are approaching the set limit. It has no bearing on your account and is there for indication only.
There's no fair usage policy in place, as you are already prepaying for all the data you use.
I trust this clarifies matters for you.
Regards
Trev
eForum Team