NTL aren't too bad in my opinion...
But I rarely call them up maybe 3 times in 6 years.
Most of the time the issues is not something that can be fixed by the user and is down to NTL and is affecting many people.
modem restart / linksys router restart solves about 90% of all problems, even if it's only temporary.
They should be able to give you a decent service, just ask to upgrade your internt connection to the 3mb or 4mp or what ever the £15.99 service is these days.
might cost you more, but think of all that extra pr0n you can downlaod
Anyway, Good luck sorting it out