Sparking Microwave

Last night, my wife tried to heat some pasta in a bowl in the microwave, and it sparked a couple of times. We called maintenance, and the technician came to check it out. He turned the microwave on and off, unplugged it, and said everything was fine. He "ran" the microwave, and since it didn't spark during his test, he told us it was good to use again. He blamed it on our bowl , and said that “it’s the shiny stuff” that’s dangerous. He said, porcelain and glass are “super bad”.

I said I didn’t think so, because our bowls and plates don’t have any metallic paints or coatings. He disregarded that, and instead he advised us to monitor it for any further sparking and to record it if it happens. This way, the complex can send in an engineer or consider replacing the microwave if necessary. I want to demand a new microwave from management because I don’t want to risk my life or burning down the place because some idiot decided unplugging the microwave was good enough.