Can anyone give reliable information about settling debts once the account has been bought by debt collectors?

If the collection agency is working for the creditor then the account has not been sold. Even so original creditors are often willing to negotiate a settlement rather than force the debtor into bankruptcy or litigation. Accounts that are purchased by third parties are usually open to settlements but only if the collector does not feel there are any other options. When attempting to settle an account for less than the full amount the debtor should always offer a lower amount than they are able to afford rather than starting with the maximum amount they are willing to pay. Please keep in mind many original creditors and third party collectors will opt for a lawsuit if the debtor lives in a state that does not allow significant protection for personal and real property. For example, if the debtor is employed and the state allows the maximum federal wage garnishment of 25% the collector may not be open to a reasonable settlement.