Hi guys,
We have the same problem. I send an information email to all our guests regardless of whom they choose to book. It states the smae, if you are going to arrive after.... It also states our office hours.
I ring the OTA concerned if we haven't heard from the guest by 8pm and tell them, they had better contact their client and let them know cos I'm going home and they wont get in! I also tell them the guest will not be getting a refund as they haven't abided by our policy which is clearly stated on all our websites. I also tell them that I will be marking them a now show and they wont be able to leave a bad review.
In the case of the corporate traveller clients and flight centre clients, i send the email to the "booker" and ask them to forward it to the guest. I have in bold letters "please acknowledge that you have read this email"
We don't have a night bell and turn the phone to an answering machine.
This has slowed the problem though not completely cured it.
hope this helps.