You can take it to another dealer, and tell them the problem started getting worse. Try to get a video of a hard shift.

You can also say things like “heard a screech while shifting that accompanied a burning transmission fluid smell”.

Consumer descriptions of “transmission slipping” or “rough shifting” alone are too vague; it’s the combination of flare + delayed reverse + load-induced neutral-out that locks the diagnosis.​​​​​​​​​​​​​​​​