Rebecca, I would seriously be checking this out further. If you don't want your EBM heated in the microwave they shouldn't do it. Both the day care centres we have used have had no problem at all with heating the milk correctly. Also, I think you will find that the WH&S regulations do NOT state that the drinks should only be heated in the microwave. I would be finding out from the relevant govt department and then standing your ground. I am sure you are worried about annoying them, but I would be more worried by their apparent lack of interest in doing the right thing by the kids in their care. Personally I think I would be trying to find another centre.