Closing account

I have settled my Edgar's account. I was offered settlement discount which i took. I was told paid up letter will take about 21 days. Today i called requesting that they close my account and send me paid up letter. The lady said i didn't pay full amount. I asked hee to retrieve phone records that will prove i paid what they said i should pay she says they don't record all the calls. What should I do to get my account closed and have paid up letter.