There should be NO excuses for this in-warranty replacement. They know there is no "fix".

Just stick to your guns. It is unrepairable.

Good luck. And if they have no respect for your problem, contact the regional service manager directly. He may tell you to resolve it locally, but after trying again, go back to him and keep complaining.

Keep records of each visit (names, times and dates etc.) and the paperwork generated each time. You may need ammo later.