Some companies of solicitors also act as debt collection agencies. Your original creditor may have sold the debt to them, and if the letters ask you to pay the solicitor directly, this is probably what has happened. Or your creditor may be paying the solicitor to collect their debts. This is usually the case if the letter tells you to pay the original creditor. The solicitor may be part of your creditor's collection department using a different name. Check the small print on the letters to see if it mentions the original creditor, or compare the addresses to see if they're similar. This used to be common practice for many banks and other creditors, but most have now stopped doing this because it can be misleading.