RE agent refuses to answer

[Anthony Buoncora]

I'm an agent trying to show a house to a client but the listing agent refused to answer the phone, texts or emails and kept declining my requests to view the property with no details or reasoning.  I have reached out to the broker but they have not responded either.  Listing agent finally responds several days later and first he says he had COVID, then said he was on vacation and the house now has an accepted offer even though there's nothing about an accepted offer on the listing.  Is there anything I can even do about this?   Is this perfectly legal or is it a breach of ethics?