[MovedGoalPosts]

The IP addy that is seen by the internet, and thus the one that you are getting banned by it that allocated by ntl's network to your Cable Modem, Or Set Top Box. Whatever you do or change to any equipment that you have behind the modem/STB will have no effect on the IP addy the internet sees. Thuse wiping and reinstalling your PC would have no effect, similarly changing MAC addy of a router or replacing a network card, has little chance of success.

The only way you will get a new IP addy is for your modem/STB to release the existing one. ntl's network, presumably operates like most networks, with an IP "lease" allocated for a period of time, often 24 hours, sometimes longer, rarely shorter. Even if you turn off whatever has the connection, the lease continues until expiry time. Thus you switch the device back on a couple of hours later and it still has the same IP. Occasionally you can be lucky and find you have disconnected, and get a new IP when reconnecting, but that is because conincidentally the lease expired and your old IP got reallocated to someone else. IP addys are allocated at random, first come first served.

Thus to guarantee a change of IP, your devices connected to the ntl network (modem / STB) need to be off for longer than the maximum lease, and when you do reconnect, somebody else will have to have already been alocated your old IP.

Of course a change in the network conditions can also trigger a new IP allocation, hence the advice to upgrade / downgrade your boradband connection.

Somehow changing the MAC addy of the modem / STB would also do it, as effectively the ntl network will see that as a new device, needeing a new lease. But to do that would be against your terms of service, so we don't even go there.