No mater who maybe right or wrong, the vendor probably has the deeper pockets if you wanted to take a legal route....
Maybe it's a sign of:
A new sales person in their organisation who doesn't know/understand/care
Tight times for them so they're chasing your leads

Either way tis the way business often works (though thru the smoke and mirrors it's not always so easy to see).
You need to decide whether you make a noise at them and live with it; or make a noise and drop them.
Ultimately if they aren't respecting their dealers they stand to loose them and along with that they'll ultimately loose the support of the customers.... unless of course there is some greater plan....