On a regular basis I call/text/email an agent to ask pertinent questions to make an offer and never get any response even after multiple attempts. 

If there is a house with a detached ADU, if the main house was built prior to 1978, it is subject to rent control.A buyer can attempt the Ellis Act, which could take months (owner occupied loans generally require the borrower to move in within 60 days) and cost $20,000+.

They keep telling me that they are attempting to get in touch with the local account rep.

This is why 90% of attempted fsbos don't sell and end up listing with an agent later on.

Concessions are also somewhat difficult to comprehend, since real estate can be a game of telephone, sometimes the transaction is just better off, without attempting to get four parties to understand the numbers. 

I would only include landscaping if the tenant covered the cost.If he's below market - even a little - and demanding I pay for landscaping while attempting to insult me with complaints, then I would get rid of him.

No one was able to clear it, even after multiple attempts, and it caused Home365 to stopped paying my bills (pending owner contribution).

Tell ya what, once you've hit journey in just 2 trades I will let you attempt to talk down to me. 

Let them know despite repeated attempts to collect the money, it is not forthcoming and that you will be starting the eviction process for non-payment of rent...then hire an attorney who specializes in evictions and get the process started.

Tenant agree that the reletting charge is a reasonable estimate of Landlord’s damages and that the charge is due whether or not Landlord’s reletting attempts succeed.