Being sued by debt collector

I reside in Missouri. Hopefully you all can help me as I’m a little confused. I’m being sued for 825.14 plus court costs. I do owe this debt but my confusion is the way it’s being handled. I can still log in and see the debt and enter into a settlement agreement with the original debt holder but when I call them they gave me another number to call and that company gave me another number for the law office that is suing.

The law office of course wants the full amount before the court date to avoid going to court. My question is, can I accept the settlement offer with the original holder and pay it off or am I pretty much screwed if I try to present that as proof of payment at this time?