Solution: Pay more
Charging by volume will allow the government to introduce an 'internet tax' very easily. I believe Belgium does this.
Anything other than uniform pricing will increase costs as the additional billing costs far outweigh any savings. Most ISPs have speed calculators for given numbers and these are generally reasonably accurate. If that says 2Mb and you get 2Mb then you dont have grounds for complaint, even if the generic advertising says 'up to xMb'.
What Wispas campaign might achieve is a huge increase in costs for the majority. Upping the cost of an 'up to 8Mb' connection to, say £30/month will allow the few to have slight reductions for underspeed lines, subsidised heavily by the rest. Bad news. The ISPs are desperate to increase their charges and they would love this plan.
Internet provision in the UK is pretty cheap when compared to a lot of countries and if you want a better service it will cost you a lot more. Telcos prefer to hand out huge profits to shareholders rather than investing in infrastructure. Witness Vodafone for example.
The solution? Check to see who offers what locally and select whichever option suits you. If you dont like any of them, then dont buy any.
To use the sugar analogy, if I buy a bag locally, it costs £1.20. If I buy at Tesco's (6 miles away) I pay 89p. I dont suggest that Tesco should increase their price to £1.20.