This can be a voluntary contract between your debt payment agency (acting for your needs) as well as your creditors.
A creditor need not accept your repayment proposition. Even in the event a creditor takes your repayment proposition, it may be cancelled if you fail to comply with most of the terms associated with contract. The creditor can then resume collection task on the debt.
You must be told by the agency within 1 month to be informed by a creditor that the creditor has do not take part in or has withdrawn from a financial obligation payment system.