I've been internally debating about a reply to this. I say: tread carefully.
Yes, it sounds very tempting to go after a big company on the grounds you are stating. However, what proof do you have that this was said to you? Did you record said conversation? If you did, it is highly unlikely that a court would allow it to admitted as evidence in any court proceedings, meaning it would be your word against theirs. They also likely can afford to hire MUCH better lawyers.
Does it suck? YES. However, as a former ETL, I would be PISSED if one of my coworkers had this arrangement. Right now I spend most of my Sunday mornings, and many times Saturday nights, involved in my church. So, for religious reasons, I want all that time off. Oh, and I have vestry meetings once a month, as well as executive committee meetings and youth group time. I want all that off for religious reasons. Yes, this is taking it to extremes, but the point is: where do you draw the line?
The bottom line is that they expect open availability - and you don't provide that.