Milk bad before we arrived home and customer service just as bad

We purchased a 2 litre of milk at Woolworths Blu Valley Mall Monday and put it in the fridge. We did not open it. The next morning when I opened the fridge it leaked everywhere. How is a WW milk not sealed? What a huge health and safety risk! We couldn't drink something that came unsealed from the shop. Who knew why it wasn't sealed or if something was added. I posted on their FB wall, they did not assist. I called customer care, they don't respond. What do I need to do to get service and this issue sorted out??!?