Ahhh, ok, now I'm on the same page.
If you want to contact companies direct with the intention of establishing a supply contract, then the department you are best off going through would be their marketing arm.
Different companies operate with different clearance structures, some have a tendering process, some will only clear through their own contracted agent, and then some will only clear merchandise through their own retail network in the way of sales.
I would suggest calling them and work your way through to the sales/marketing department, but prepared for some frustration as the usual game will be you talking to 20 people who all want to pass you on to the next 20, and so on.
First part in this process is finding out just what their clearance distribution policy is, from there you will be able to find out how to get your foot in the door, providing they have a door of course.
As you have noted, the top name designer brands in this industry is very well protected, the last thing a designer brand wants is their products being devalued through surplus sales, that,s not at all good to maintain there over all retail value in the marketplace.
Those that protect that best won't even sell through their own channels to clear stock, they will simply burn it if they have to, because that maintains a high retail value for their brand name.
Sorry for my earlier confusion, but hopefully that was a little more helpful.