Dell Financial Services Rip Off?

So, last month I make the final payment on the Dell PC I bought for my daughter to take to college last year. The payment was due on October 1st.
On 9/29/2007 I paid my account in full in accordance with the terms of the deferred interest plan.- I even spent the extra $9.95 to make sure I got "same day" processing - My account had a zero balance.
I get my final statement and on October 8th, they posted $96.27 in deferred finance charges to the account.
I contacted Dell by phone and the agent thanks me for "trying to keep my account in good standing" and tells me they'll "waive the charges" as a one time courtesy... Like I've made some error!
The charge still appears on the online account summary. I sure hope they get this fixed... you know you would think that computer guys could set up their software so you don't get charged when you make the payments on time... unless they're just trying to rip you off.