Owners/service Manual problems of the 2010 Ford Edge

I was attempting to park on a steep incline in san francisco on a rainy day, because I was aware that my vehicle tends to roll backwards upon releasing the brake (even when in drive), I decided to not park in that spot and was very careful to shift into drive and gun the gas so the car would move forward and not roll back into anything behind me. I had successfully used this technique before, but this time gunning the gas still resulted in my rolling backwards and caused a collision. After the collision, reapplyong the gas made the car move forward, but now the damage was done. I do not know if this is a gear selector peoblem, an issue with the car in the great deal it rolls back on hills, or a combination of both, but this is definitely a safety issue and was not brought to our attention when purchasing the vehicle or in any of the safety information we read to date especially considering the hilly environment in the bay area. If the vehicle had a manual 4wd selector like my old Ford ranger did, switching this on would resolve this issue on hills, and allowing it to be shut off during normal drives would still reserve the fuel economy that Ford was going for with this model.