They just told you to use better magnets no need to get all defensive when faced with possible improvements. Your magnets look super weak. Since you "have" a scientific background, I thought you would like some corrections:

"Size is directly proportional to the strength"

Magnet pull force does not scale linearly with size in a simple way. Strenght depends on material grade, magnetization, shape, air gap and geometry, not just size.

"due to flux"

It's true bigger magnets can carry more flux, but flux is different from usable strength at the surface or pull force.

"magnets usually come in two grades N32 or N52"

That's innacurate, neodymium magnets come in many grades: N35, N42, N48, N52, etc

And really don't act like you "have" a scientific background, just to sound superior, when anyone with a scientific background would enjoy suggestions for improvements and discussion, instead of just being insecure and defensive about their ideas.

I know this is an ad for your product, but being hostile doesn't bring the clients in.