Landlords not receiving my messages

Hi,
I have messaged numerous of landlords and have had no replies I thought this was strange so I messaged my friends account who is a landlord with a property and my message also did not go through to him, I have called open rent numerous of times to try and get this sorted and they keep on saying a customer agent will get in touch with me in 24 hours but no one is getting in contact.
Lamar