Now he (the buyer’s agent) is not communicating at all.

This impacted communication and I believe they became complacent or too busy to care about the property.

This is an important tool for anyone buying a tenant-occupied property.Once you close on the place, you should provide the tenants with a letter that introduces yourself and gives them basic instructions for paying rent, communicating with you, and submitting maintenance requests.

Don't talk to him in person; only communicate in writing.

You need to figure out how to do that by, ideally, communicating with the debtor/tenant or possibly hiring an attorney or collections to do what they do.Regarding your mention of other costs/damages, what are they?

Ask, ask, ask other investors and home sellers in your area who they've used and what their experience was.And try various agents out by getting property comps from them just to see how well they communicate, how professional they are, how aggressive they are.

Can any refer a good PM company or person that have had great experience managing their property(ies) and great communication with clients?

I recently watched a video on the Bigger Pockets YouTube channel that discussed the career as a side job and have become highly interested.

I started out that way and a selling point I used was that they are getting double the commission as a buyer/listing agent, you'll find that some agents might communicate a little faster for you. 

I also have a drop slot in the building that they can put rent or any other paperwork/communications they need to get to me.