The villages of Redbrook, Newland, Clearwell and Penallt have been without a Vodafone signal since the middle of March (see Monmouthshire Beacon story here). It appears that there is a problem with the mast on the Kymin which supplies the areas concerned but no date has yet been set for rectification of the issue.
More information is also available here from Vodafone's forum.
11/4/2013: An update is available from the Monmouthshire Beacon here.
18/4/2013: A further is available from the Monmouthshire Beacon update here.