Re: New T&Cs
"he users who signed up for the service in the beginning did not sign up for this, and there is no right to foist it on them now under pain of banishment."
Um... yes, there is. They can refuse to deal with you if you refuse the T&Cs. This also applies when, just for example, your bank sends you a letter informing you that they've changed the T&Cs on your bank account. Try writing back to them saying they've no right to do so and that you'll take them to court about it. In fact, try asking your legal representative if he thinks you'd have a case.
Just because you signed up to a service at one point on one rate does not mean that you have a legal right to receive it at that rate forever after. And that's a GOOD thing - otherwise, your employer would never need to give you a pay rise. Ever.