"Illegal" is simply training jargon. Same thing with "illegal connection" for air travel.

But, the underlying issue is entirely reasonable. If you want to work a deal with a property, deal with the property. Some agent called a "concierge" to make you feel that you're special isn't going to have more impact than you.

I would call the sales manager and not discuss the one stay, but rather the ongoing business. Maybe even negotiate a rate based on $ volume and see what you can get.