Do not judge a company by their BBB rating. "BBB Accredited" simply means the company paid a fee to join. I called the BBB because my business had a "C" rating. I was not a member and they told me the rating was based on the small amount of information they had. I answered all their questions. Based on that and the lack of complaints, our rating is now an A+.
I have not worked with this company or any like it. However, even when they get your debts reduced that doesn't mean that you will suddenly have a good credit score. And when a debtor reduces your debt they will send you a 1099 stating that you had "income" from them which is taxable. If you negotiate with a debtor, make sure you get everything in writing including that they will not issue a 1099.