In EU for instance telcos, banks etc often change conditions without "negotiation" they simply inform their customers that starting from the next month/year/end of auto-renewal period there are new conditions visible "there" and if their customers refuse the change can end the contract without penalties having, in theory, enough time to switch to another company.
This protection is not much effective in many cases since most telcos/banks etc offer nearly the same conditions and change them nearly at the same time so a "bad move" for a customer of company X typically is already present or about to arrive to others possible "competitors", regularly antitrust step into action but normally without enough strength and timing to really avoid many bad moves...
However no one can act without enough time from the over part to respond and certainly not without keep receiving money on behalf of anyone...
Oh, to clarify I hear about cases arrived in curt with motivation like "we have received (as proved by Postal Service) that communication, but inside the envelope there are only to white sheets..." and things of that level but still person to person actions with a formal responsible from both sides.
Generally, limited by terms of the contract with the customer, sure. But most consumer online services have contracts that provide broad discretion to providers.
Some particular services are subject to additional public regulation.