Our son does the preliminary designs and renderings, then we have an architect do their notes, etc.

Since THAT involves some kind of maneuvers that look too much like money-laundering (generating fake invoices that plastiq 'needs' to see, for services not really rendered, etc), I'm not doing that.

I would absolutely never hand any contractor $15k for services not yet rendered.

Now as far as your rendering question goes - what is your price point? 

Talk to city manager, zoning, city officials about what you want to do have 3-D renderings and 2d floor plan and elevations ready to show.

If not, a court could toss out your liability protection rendering the structure useless, and your personal assets become available. 

There are ways for a broker or servicer to charge a note holder for services rendered and lighten up on the cost of borrowing in a new loan, all playing within the rules, legally and ethically!

What additional services are rendered to collect the late fees?

That's not the way professional companies do business - if legitimate services were rendered, then you collect for said services.

This has rendered the property unmarketable and unsaleable.I am writing to formally request that your client honor the terms of the contract and undertake the necessary action to fulfill the contract terms.If the property is not able to be separated from the condominium, I will only be able to sell the building at a fraction of the price.