Yes.
If you use a stand alone cable modem you can upgrade using the following link:
https://autoreg.autoregister.net/cgi..._tiermigration
If you are using a Set top box for your broadband acess you need to call NTL (0800 052 2000) and selection option 5.
There is another Speed Upgrade Thread on this forum. Everything you need to know is in there.
Phil.