Even in my heavier downloading days never used 75GB, that was downloading bits of everything, games, DVDs, albums, etc, etc. This was both having 2Mbit/s unlimited ADSL and as an ntl 3Mbit sub.
Only thing was I didn't feel the need to collect a load of garbage I didn't actually need. Do people really need 15+ DVDs a month? Are you ever actually going to watch that stuff? Probably not.
Another thing I actually find being told to go on a surfer's package because I don't download loads quite amusing. Some of us just like to get our occasional downloads done faster and its' our prerogative as the people who subsidise uneconomical use to do as we please.
No high paying low using customers = prices going up for those extracting the urine, fairly simple isn't it?
If you are stuck on 512k you're probably absolutely right, just phone up and ask to cancel and the people in retentions who have been commanded from on high to keep you whatever the cost will be quite happy to regrade you, discount you, love you, hug you and probably send the local 'working girls' around to service your manly needs (or the local giggolo for those ladies). ntl have minor issues understanding that retaining unprofitable customers doesn't equal profit so you should be alright
Always ignore
most ntl salesmen, they tend to be full of faeces as most salesmen are, and will quite happily promise you that your cable modem / STB comes with a fellatio attachment if they think it'll help them get the sale - these are the dangers of commission based sales and why I personally try to avoid dealing with salesmen whose income is commission based.
Anyway please continue complaining, careful not to bite the hand that helps pay for you though

Celebrate the low users don't dig at them