Alas, the phone is what you'll have to use. :( Also the rooms are only held until 17 April, though as Alex said we think a few are still available.

If they have any issues finding the booking, make sure you're speaking to Reservations, not Reception, but as long as you're calling during business hours, that's who you ought to be speaking to automatically.

If you do have any problems, let me know and I'll see what I can do to help. :)