OneMain Financial in North Brunswick Township, NJ

First I apologize for my poor English I am a single father of twin and I went to his company to get a loan for my divorce and pay off my credit card debs. They gave my $5800 for 60 month at 29.99% APR my payments are $189.00 a month but I pay $200.00 I got the loan in November 2012 I never was late also my payments are the 20th of each month one day I decide to pay on the 8th just because I got the money earlier the next month I couldn't pay earlier so I make the payment on the 20 and they charge me all the $260.00 that I pay that day for interest, of course I call them and they say that the charge was because the month before I paid on the 8th I explained why I did it and I told them that I thought I would have a good record with them if I pay before of due date their answer was They are not a credit card company and if I pay before or after the 20th I would have penalties since then I pay every 20th now I have $4784.00 to pay I was thinking to pay it of with my tax return so I can get rid of them. Oh the costumer service sucks they treat me like crap specially one of the woman that work there in the North Brunswick branch every time I call to speak with the girl that helped me with my loan or the manager she say to me OH IS YOU!!! with bad attitude and then she always say that THEY ARE IN LUNCH OR THEY WENT OUT she never transfer me to the people I need to talk