my dad replaced the front shocks on my car without changing the back, not even 10,000ks ago, and the suspension is already worn out, when i go over bumps in corners while turning, the bottom of the car will hit the road heaps hard cause the suspension is worn, how could it of worn out so fast, could it be cause the back shocks wernt replaced also?

If your car is hitting the ground, the jounce bumpers (small, dense blocks of rubber in the suspension) are not installed. Look in the upper and lower control arms. They should be there.