Green Tree Servicing LLC Continually file unnecessry interest on to this account. Rapid City South Dakota

You are missing a lot of details but from what you did post the biggest problem is that you don't seem to be paying either on-time or for the full amount.

If your payment was constant every month and appears to be $90/month.  In 6 years if you have made every payment on-time you have paid a little over $6400.  Your balance has gone down about $2300 which at a quick glance looks about right, if anything it looks like you have reduced it by more than it should be.  As you always pay more interest at the beginning of a loan than you do toward the end.

Now, your statement does look a bit confusing but some of that may be the formatting.  It would also probably be a bit less confusing if you posted more than just a single statement.  But the key to this statement is a few things. 

It appears your payment is due on the 16th of each month and your payment is $90, your last payment was only $45 and made 4 days after the due date.  When you are late they charge you what looks like a 5% late fee making your next regular payment $94.50.  It looks like you MAY be making partial payments (perhaps 2 $45 payments).  But again since the last payment was 4 days late you are charged a late fee. 

I will say the first thing you probably need to do is make sure you pay them $94.50 before the 16th in order to avoid additional late fees.

As for the payoff amount, that is probably correct.  Your statement date was 01/23, since then you have accrued additional interest.  So the $75 extra almost 20 days later is that extra interest between the 01/23 and when you called on 2/10.