512k was a broadband speed offered by ntl as standard product for a while. If I remember rightly it was when the 3 service bundle with 1Mb BB cost more, so was for those people who only wanted to pay £30
However it is not kind of an orphan as it was never included in any upgrade plan.
Unless you get the account holder to speak to Customer Relations it is going to cost more to upgrade (by £3.01) but then the bundle you are on is going up by £2 anyway from the 1st June (as are all old ntl bundles), so might be a good excuse:
'Phone these people and they can make sure you don't pay more. Oh and they will make our broadband go faster'
