We have had similar issues...
I have spent $25k on one Crestron programming project alone (we designed, purchased and installed all the gear - we just needed the programming). After getting taken to the cleaners on some other projects I just write up in the purchase agreement that all the source materials are ours - we are paying for the IP. Never had any static, but I can tell they are hesitant at times. However, 100% of $25k is better than 0% - so we don't have trouble finding an outfit to do the work. There really isn't many environments where you have that relationship, where your product you are buying is held hostage like that. If you have a building designed and built, you get the blueprints, the materials cost, the as-builts, etc. you don't have to call the contractor 3 years later and pay him $2500 to tell you where this one conduit goes. It's on the engineer's drawings (that you own a copy of).
Also, we have moved on to similar projects with similar gear and setups and it's nice to have that source material as a base. Previously, the programmers acted like they were starting over each time and there was all these man-hours involved - when they were basically editing what was 95% done (and designed by us anyway). Now we can say, 'we just need these precise edits - how many hours is that?'.
Regarding the OP, I have found that the Crestron/dealer/programmer relationship is opposite of many in the high-tech sector. In most cases, your vendor has your back and you tend to run into the big, monolithic manf. as the problem. We have had nothing but great luck with Crestron itself. Overnighting parts, speaking with engineers directly and getting real answers, etc. Our rep is always hooking us up and 'mediating' between us, crestron and the programmers and vendors we use.
If I was the OP, I would go directly to Crestron and get the local rep on your side. Perhaps there is something they can do. If you are buying a house where the BANK installed a programmed lighting system I imagine it's not a cheap place and the people roll with perhaps have the desire to have a similar system. If instead, all the system does is infuriate you and you associate that with Crestron it doesnt help Crestron at all. The rep should understand that.