need help

Last year we filed bankruptcy (a ch 7) and now we are in the process of trying to rebuild our credit. I know that the ch. 7 will stay on my report for 10 years so I want to make that my only flaw. I do have a collection on there from the gas company at the old house for $700. I really can afford to pay all of it now, but I was hoping to maybe negotiate it down a bit. I tried to write a letter to them asking for some kind of agreement. I have never heard anything back from them. I tried to call once with my cell, and the guy kept calling me back on it non-stop for a month. (and I never gave him my number!) How can I get them to work with me through letter writeing, I want everything documented? The collection is through Alliance One if that helps?