call barring of witheld numbers not working

[#1]

Just had an illegal call, robot trying to sell double glazing (windows classic blah blah). I have had call baring set on witheld numbers for months but when I did 1471 on this call it was number witheld! In case of any use call was logged at 11:39.

I checked my barring options and it indeed has number witheld set on.

Is this some new clever scam or is your service intermittent ?

[#2]

As far as I'm aware some international numbers are displayed as Withheld but can slip through the net due to the call originating from abroad.

Hopefully it doesn't happen again.