Estate Agent Philip Mostert not responding to prospective buyers

We have the house that we were interested in, we contacted the agent (Philip Mostert) that selling the property and he is not responding to our chats and he just blue tick and nothing after. We tried to call him still no response. That a bit rude or there is hidden agenda behind him not responding to us while the house is still showing its for sale, even if the property is already sold Philip should have the decency to respond and say the property is already taken,etc and not just read the message and provide no response.