I don't think they should be on the hook for providing people with free service that costs them money if they need to change the terms, but it should be 100% manual opt-in (with people who don't opt-in having their service canceled) if it involves a price increase or wholly new charges where there were previously none.
Based on the fact that their apology seems centered around the email bug and not the initial premise of adding charges without users having to opt-in to them, I have to disagree with some of the comments here that this proves they "get" customer service.