[KiWinUS]

In my 55+ years of working on autos it is very rare gaskets fail without help. eg. loose bolts. Uneven surfaces. Mismatched surfaces. Lack of surface area. Excessive exhaust system movement to list a few.
Did gasket leak between manifold and block or manifold and exhaust.
If block to manifold after cleaning both apply a very thin coat of grease to manifold and then bolt to block without gasket torque as normal and then remove. Now look at block mating surface to see grease mark contact area. This could show a potential issue. If it’s manifold to exhaust you can pretty much take it to th bank it’s not the gasket.
I n the world we live in today I’m not surprised the company has not responded. The profit on the gaskets i feel couldn’t support such service unfortunately. And what can they tell you without seeing your vehicle to gather all the facts.
Good luck.