Obviously they are not mechanics...They are just sales people.
It would be easy to find the noise if they were really "mechanics".
I suspect they thought the noise was coming from the transaxle since they installed "an additive". Differential gearsets are cut and honed to mitigate gear whine. No additive will help a poor gearset...You would need a transaxle gearset replacement. A differential whine is not really a problem except the noise is annoying and you paid EZGO for a "silent" transaxle at purchase.
They are obviously just trying to get you to go away. What you fail to understand is that the quiet transaxles are the ones with problems...not the noisy ones. Tell them you want your problem-free noisy transaxle replaced with a quiet problematic one
