If they refuse you have at least claimed it and can document your claim so corporate Marriott can't say, "Well, you didn't make a claim."

What Marriott desperately needs is a separate hotline or email to report noncompliance that is actually monitored and handled promptly. You shouldn't have to call a reservations/customer service agent and expect them to have the expertise or ability to force a given hotel to comply, if you're still at the hotel.