Spoilt long life milk before its even opened

I recently purchased 3 long life milk. Two of which I intended to use on Thursday to bake as it was my daughters birthday. I opened 1 and noticed it smelt funny. I then opened the next 1 as I needed it. Both was off. I then shook the next 1 and realised it was absolutely thick. All the expiry dates were different. I threw away the other 2 as it was unsanitary to keep these open in my house with a baby around. It was only till later did my sister tell me to put it on hello peter. I have the 1 unopened spoilt milk. So disappointing as I couldn't bake the cake. I had to go and buy a cake and it was too late to bake. I purchased the milk from Game stores in west street. And the expiry dates were Dec and Aug.