Yes. You can do it on your own but companies can usually get larger settlements. You on your own are doing one...where as if they have 10 different people with a card from abc bank, totaling 100,000 in balances, they offer 40,000...a bank usually will not say no to that much. You on your own...are doing a much smaller balance and therefore really have no negotiating power. I work for a company that does this and depending on your credit can save you a ton. If you are though, I would not recommend it. If your credit is already showing late fees, 90 days behind, etc. Then go for it. Your debt to income ratio will drop drastically.
Before applying debt consolidation or debt management , i would like to look companies trustworthiness.