Can the owner just do anything he wants and what are my rights as the tenant?

I rent an apartment with my husband. During the day, it is only my four month old daughter and I. I've asked for a call anytime someone is going to show up and was told it would be put on file. A man has shown up multiple times demanding to be let inside. I haven't gotten the first call or notice. The real estate company says he is the owner. He hasn't introduced himself once and is rude and intimidating. What do I do?