Building a new home, have sketched floor plan

[Duppers]

12. The 16hrs has turned into 22+

The $1800 charge for the "CAD Plan Cost" is what we don't understand. What is it for?
It's on top of the hours charged.
Is it paying for software programming update, which they should already have? OR is it for one hard copy blueprint?

We took an online floor plan the builder had already built, hacked the bottom floor off, made some minor changes, and asked they they draw it up. Paid $3k upfront. But we have been asked for an addition $450 for 6 additional hrs with possibly more to come just for the modified CAD plans. Am I being unreasonable or too cheap?

On edit: the builder has no input at this point. All design work being done is by us and the CAD designer. She works for him tho.