De-glossing a matte decal?

I had a customer with a new truck come in today with a shiny spot on his matte vinyl decal on his hood today. I work for a dealership, so we don’t have dedicated products for everything. I tried our APC and a microfiber on the spot and that didn’t touch it. It appears that some wax accidentally got on the decal and was rubbed into it. Is there any trick to restoring a matte decal once it has been shined. Does a dedicated matte cleaner work in this situation? I feel like there’s no going back once this occurs.