Good Fences Make Good (oops... fence problem)

What is the name of your state?
GA

We had a back yard picket privacy fence installed 14 months ago. After a windy day a few weeks ago, one section of the fence consisting of 6 posts and the rails and pickets became unstable. 3 posts were leaning over, and another 3 were loose. We called the fence company, and they quoted a price of $300 to re-cement the 6 posts and $150 to set new posts in between the leaning ones. They sent a representative out. He looked at the fence, and told us that the posts that were leaning was due to a bad installation. The leaning posts were only set 12" deep, instead of 24". He had a crew with him, and they installed 7 new posts among the leaners. He also said he would tell the fence company owner that we should not have to pay anything because of the faulty installation of the original posts.

We got a bill for $450. It was for the $150 to recement the leaning posts (which was not done, because recementing the 12" deep posts would not be beneficial, per the fence crew foreman), $150 for installing new posts, and $150 for Trip/Labor. When we complained about the bill, the fence company said they would take $100 off the bill.

Do we have any recourse? Do we need to pay the bill, then go to small claims court? Or should we refuse to pay, and wait for them to take us to court? We don't want to damage our credit, but don't think we should have to pay for the fence company's shoddy work.