Yes? Why would you think they couldn't? They just can't change you more or change your bandwidth based on the services you use.

What I really want is something akin to guarantees on the bandwidth, or something like 95%ile billing. Why should I pay for something that I'm not being given (and yes, before people start saying it's legal because of the contract, I'm not arguing that, I'm saying they're selling 50, I'm getting 20, consistently.)