Toyota Corolla: Rolling backwards

I HAVE just bought myself a Toyota Corolla Levin ZR and traded in an Astra TS Classic. Everyone tells me to buy an automatic because they are better to drive and don't roll back on hills, but this car is not designed for steep hills. This car will roll back the whole way down. If I'd known it was going to do this I would have bought a manual and saved the money on the auto transmission, because really, you have to drive it like a manual on steep hills (minus a clutch). The Astra Classic did not have this problem. Why is this the case? I know I can do nothing about this now. The dealer says he can't do anything about it.