Understood. And you either did, or did not enter into a contractual agreement with them that they would not make changes without approval.
But for some reason maker didn't sign the quality contract with us.
OK, so you did NOT enter into said contractual agreement...at least not that one...are there others? PPAP, purchasing contract, etc.?
A very big "oops" on your side, but you choose to do business with them anyway...your call. But you can no longer 'force' them to play by your rules.
If they are IATF, they must pay attention to your request...but they are not required to follow it.
The balance of this is that you are not forced (by them) to buy from them either.
If it is catalogue part - part for free market, which I can buy freely, to whom shall maker send change notice?
To those with whom they have agreed to do so, which apparently does not include your company.
I buy paper from OfficeMax...I have no agreement with them...they can change paper any time they want.
I buy material to spec from another vendor, with an agreement in place that no changes are permitted to rawmats, process or packaging. They have contractually agreed to get my approval before making any changes.