Surprisingly few people know how this works, that the banks and other lenders "sell" your indebtedness to privately owned Colletion Agencies often for less than the amount owed, then they can do whatever they like to collect it, impose "late fees" if payment on a supposedly scheduled payment plan. These fees, unless paid in full immediately, are added to the amount owed which increase the total amount of interest that will have to be paid.
The other version of the scam is "Debt Consilidation." These companies take all your debts and "negotiate" with the banks to accept a reduced interest rate if they, the Debt Consilidation companies mark the payments to the banks guaranteeing that the payments will be made if you give the agency one large payment a month. If you need to be late with a payment then they add a fee to what you owe and threaten that if it ever happened again, the deal will be off and you will be back to owing the money to the banks at thr original higher interest rate they were charging you.
I went that route but soon went back to making my own payments and the banks let the lower interest rate that the Debt Consilidation company had negotiated stand. The banks were inflexible about renegotiating the payment due date. If a payment were to be late, they informed me, they feel that they had been given the right to raise my interest rate to whatever they wanted.
It took years and careful bookkeeping and scrupulous payment making but I was able to get the debt load off my back and am now debt free and will do to remain so.
The only thing I learned was during the early stages of the debt crisis when I was getting harassing threatening calls from the Collection Agencies who had bought my debt, I could get them to back off thr phone calls and lawsuit threatening mail by saying:
"It is my legal responsibility to inform you that this call is being recorded and the contents will be reviewed with my attorneys to evaluate your compliance with the Fair Debt Collection Practices Act." Of course the calls were not being recoded and I had no attorneys.