DS went with EBM and it was fine. He was 9mths when he started and we filled out a sheet of what he drank, ate etc. We just highlighted it was EBM not formula and to heat in the bottle warmer and all was fine. They had a microwave there for other bottles, but there were occasions I arrived early and they were heating up DS's in the bottle warmer so I never had any concerns they were doing it wrong.