Replying to Car suspension question

I drive an 06 Xterra Off Road edition and took it in to get serviced last week. They saw 3 out of four shocks were completely shot so I gave them the okay to replace all the shocks. They replaced them with Bilstein heavy duty shocks, but the ride hasn't felt quite right since getting out of the shop. Whenever I go over a small bump they car continues to bounce two or three times after hitting the bump. I took it up a dirt road and it felt like the shocks were completely rigid and basically useless. The Xterra has coilover shocks, so could it be the coils that have gone bad or is there another part of the suspension that has gone bad?