It's a bummer, but hotels refusing to help with reservations have become increasingly common over the past few years. The trouble with cancellations, and the effort it takes to secure reservations at in-demand restaurants are but some factors. I remember when affordable hotels like Park Hotel would agree to dial into a restaurant at exactly 9am the day reservations open to get me a spot, but those days are long gone. These days, even "luxury" hotels like the MO take forever to reply emails due to demand for reservations, and I've had restaurants refuse the TSH concierge and direct me to book online.

That said, Hoshinoya has always had troubling reports regarding service. E.g. being rather rigid regarding checkin/out times and charging by the hour, even when there's availability.