If you buy a used one you are only moving it once (or zero times if you pay for delivery). 

This doesn't require a signature.So, what I think I'd do in your position is just send her notice with proof of delivery - I just used the USPS priority mail envelope with proof of delivery, with a copy of the new lease and a letter saying please be aware that all of the terms of the enclosed agreement will be enforced beginning thirty days from proof of delivery of this document and that you hope she will continue to be a tenant in the property (if you actually do), and then maybe include something about please let you know if there are any maintenance issues that need to be addressed.It doesn't matter if they sign for anything. 

so pretty much, by contract it's already "non-refundable" assuming there's no issues with delivery of property etc etc?

I'd never want to cross any legal boundaries.I'm not certain as to what the exact legal definition of occupancy is in terms of tenancy, but from my point of view, an occupancy would be something that included a leasing contract, payment of utilities, delivery of mail, tenant implements their own furnishings, etc.

Under value and over delivery to keep your units filled and your pockets full.

Now, after you've refused to rent to someone, and they wind up homeless, they land on the city's doorstep, and the city listens to their sob story, decides you are wrong, and suddenly you have tax audits, building inspectors, and enough alphabet soup to DROWN you in your life. 

What you can do, is send notice via USPS mail with delivery confirmation. 

If the tenant is not expecting to see me on their doorstep, they are also not prepared to cover-up their rule breaking behavior.

I said the letter sent by CSC clearly indicates that the increase is due to "investments in people, systems, technology and service delivery", and not a fee related to occupying the space.  

I would save their phone number and mark it DO NOT ANSWER  Thanks, I set up my cell phone so that if he calls again, he gets an immediate delivery of a pack of angry aggressive breed dogs by drone.